Sea to Summit Amplitude AmIII Sleeping Bag Regular
Designed for those of us who love space, versatility and plush comfort, the Amplitude sleeping bag is ideal for outdoor adventurers who return to the same campsite every evening, for car camping tours or cabin expeditions. Many amplitude adjustment options help to adapt to different temperature conditions. Close all zippers and pull the internal drawcords together to ward off cold. In more summery temperatures, the zippers allow for variable ventilation settings and can even transform from a thick sleeping bag into a slim summer blanket. Vertical chambers above the chest area ensure that the high quality 750+ loft down does not move while sleeping, creating cold spots. A lateral chamber barrier maintains the 60/40 fill ratio and ensures that more down remains on the top of the sleeping bag for maximum thermal insulation. Large zipper channels prevent body heat from escaping. The specially shaped foot box and three-dimensional hood ensure that the down is not compressed. Due to the specially developed fastening system with removable straps, the Amplitude sleeping bag can be connected to all our sleeping mats. This gives you the ultimate sleeping system for maximum comfort.
Designed for those of us who love space, versatility and plush comfort, the Amplitude sleeping bag is ideal for outdoor adventurers who return to the same campsite every evening, for car camping tours or cabin expeditions. Many amplitude adjustment options help to adapt to different temperature conditions. Close all zippers and pull the internal drawcords together to ward off cold. In more summery temperatures, the zippers allow for variable ventilation settings and can even transform from a thick sleeping bag into a slim summer blanket. Vertical chambers above the chest area ensure that the high quality 750+ loft down does not move while sleeping, creating cold spots. A lateral chamber barrier maintains the 60/40 fill ratio and ensures that more down remains on the top of the sleeping bag for maximum thermal insulation. Large zipper channels prevent body heat from escaping. The specially shaped foot box and three-dimensional hood ensure that the down is not compressed. Due to the specially developed fastening system with removable straps, the Amplitude sleeping bag can be connected to all our sleeping mats. This gives you the ultimate sleeping system for maximum comfort.
Designed for those of us who love space, versatility and plush comfort, the Amplitude sleeping bag is ideal for outdoor adventurers who return to the same campsite every evening, for car camping tours or cabin expeditions. Many amplitude adjustment options help to adapt to different temperature conditions. Close all zippers and pull the internal drawcords together to ward off cold. In more summery temperatures, the zippers allow for variable ventilation settings and can even transform from a thick sleeping bag into a slim summer blanket. Vertical chambers above the chest area ensure that the high quality 750+ loft down does not move while sleeping, creating cold spots. A lateral chamber barrier maintains the 60/40 fill ratio and ensures that more down remains on the top of the sleeping bag for maximum thermal insulation. Large zipper channels prevent body heat from escaping. The specially shaped foot box and three-dimensional hood ensure that the down is not compressed. Due to the specially developed fastening system with removable straps, the Amplitude sleeping bag can be connected to all our sleeping mats. This gives you the ultimate sleeping system for maximum comfort.
Designed for those of us who love space, versatility and plush comfort, the Amplitude sleeping bag is ideal for outdoor adventurers who return to the same campsite every evening, for car camping tours or cabin expeditions. Many amplitude adjustment options help to adapt to different temperature conditions. Close all zippers and pull the internal drawcords together to ward off cold. In more summery temperatures, the zippers allow for variable ventilation settings and can even transform from a thick sleeping bag into a slim summer blanket. Vertical chambers above the chest area ensure that the high quality 750+ loft down does not move while sleeping, creating cold spots. A lateral chamber barrier maintains the 60/40 fill ratio and ensures that more down remains on the top of the sleeping bag for maximum thermal insulation. Large zipper channels prevent body heat from escaping. The specially shaped foot box and three-dimensional hood ensure that the down is not compressed. Due to the specially developed fastening system with removable straps, the Amplitude sleeping bag can be connected to all our sleeping mats. This gives you the ultimate sleeping system for maximum comfort.
in 3 offers
The lowest price for Sea to Summit Amplitude AmIII Sleeping Bag Regular right now is $454.30 at Sherpa Outdoor Gear, compared across 2 retailers.
The all-time low was $454.30 on 24 May 2026. That's the lowest price we've ever tracked — a great time to buy.
Prices last updated 7 June 2026.
Last updated at 07/06/2026 18:03:10
Sea to Summit Amplitude AMII Sleeping Bag (Regular)
Free delivery between 11–15 June
Sea to Summit Amplitude AMII Sleeping Bag l Size REGULAR l Summit Gear
Free delivery between 10–18 June
Sea to Summit Amplitude AMII Sleeping Bag l Size REGULAR l Summit Gear
Free delivery between 10–18 June
originally posted on snowys.com.au
Have been looking long and hard for a good lightweight winter bag. The canvas bag I currently use is great but it's 4kgs and super bulky taking up heaps of room. The AM3 ticks all my boxes and being tall I got the long version, great construction and possibly the most comfortable and warmest bag I've ever slept in. Its was -8.5 Celcius outside in the wind chill and I was warm as toast inside this and the swag. Foot ventilation is great and the whole bag can zipper open like a quilt cover. Best of all it packs down to about the size of a 2lt soft drink bottle in the compression bag and at 1.6kgs is super light weight. It also rolls up nicely in my swag and you barely notice it.
originally posted on REI
Amplitude 5 degree bag has good isulation in chest area but very poor insulation in foot area. I got in this bag in my family room today and my chest area was warm but my feet were not. Sure enough the top area feels like it is insulated better. Not to mention sea and summit bags have narrow sewn seems on the top of the bag were the down insulation can't shift as much, which keeps the insulation even all over. At the bottom, from about your knees down, the seems are about double as wide. Making the insulation a lot more movable so you can have a lot in one part and zero in another. Quality of this bag is superb. But this huge, huge, flaw is a deal breaker. My foot area is were I need most insulation at night. This bag is the complete opposite. I saw all there bags ... MoreAmplitude 5 degree bag has good isulation in chest area but very poor insulation in foot area. I got in this bag in my family room today and my chest area was warm but my feet were not. Sure enough the top area feels like it is insulated better. Not to mention sea and summit bags have narrow sewn seems on the top of the bag were the down insulation can't shift as much, which keeps the insulation even all over. At the bottom, from about your knees down, the seems are about double as wide. Making the insulation a lot more movable so you can have a lot in one part and zero in another. Quality of this bag is superb. But this huge, huge, flaw is a deal breaker. My foot area is were I need most insulation at night. This bag is the complete opposite. I saw all there bags and they all have this flawed design. Wow. How did this ever design ever make it through approval. With sea and summit. Maybe they need to hire me.
originally posted on evogear.com
I got sick of feeling like a mummy so I decided to change my sleep system. After trying out a few quilts I realized that I really wanted a real sleeping bag but with a wide foot box. Compared with the big Agnes diamond park this bag is roomier, lighter, more comfortable and warmer. This is the only sleeping bag on the market I have found that doesn't make me claustrophobic. Well done sea to summit
| Snowys Comfort Rating | −8 °C |
| Lower Limit | −15 °C |
| Shape | Contoured Rectangular | Ultra−wide Circumference |
| Fill Ratio Top/Bottom | 60/40 |
| Max. User Height | 183 cm |
Sea to Summit Amplitude AMII Sleeping Bag (Regular)
Free delivery between 11–15 June
Sea to Summit Amplitude AMII Sleeping Bag l Size REGULAR l Summit Gear
Free delivery between 10–18 June
Sea to Summit Amplitude AMII Sleeping Bag l Size REGULAR l Summit Gear
Free delivery between 10–18 June
Have been looking long and hard for a good lightweight winter bag. The canvas bag I currently use is great but it's 4kgs and super bulky taking up heaps of room. The AM3 ticks all my boxes and being tall I got the long version, great construction and possibly the most comfortable and warmest bag I've ever slept in. Its was -8.5 Celcius outside in the wind chill and I was warm as toast inside this and the swag. Foot ventilation is great and the whole bag can zipper open like a quilt cover. Best of all it packs down to about the size of a 2lt soft drink bottle in the compression bag and at 1.6kgs is super light weight. It also rolls up nicely in my swag and you barely notice it.
Amplitude 5 degree bag has good isulation in chest area but very poor insulation in foot area. I got in this bag in my family room today and my chest area was warm but my feet were not. Sure enough the top area feels like it is insulated better. Not to mention sea and summit bags have narrow sewn seems on the top of the bag were the down insulation can't shift as much, which keeps the insulation even all over. At the bottom, from about your knees down, the seems are about double as wide. Making the insulation a lot more movable so you can have a lot in one part and zero in another. Quality of this bag is superb. But this huge, huge, flaw is a deal breaker. My foot area is were I need most insulation at night. This bag is the complete opposite. I saw all there bags ... MoreAmplitude 5 degree bag has good isulation in chest area but very poor insulation in foot area. I got in this bag in my family room today and my chest area was warm but my feet were not. Sure enough the top area feels like it is insulated better. Not to mention sea and summit bags have narrow sewn seems on the top of the bag were the down insulation can't shift as much, which keeps the insulation even all over. At the bottom, from about your knees down, the seems are about double as wide. Making the insulation a lot more movable so you can have a lot in one part and zero in another. Quality of this bag is superb. But this huge, huge, flaw is a deal breaker. My foot area is were I need most insulation at night. This bag is the complete opposite. I saw all there bags and they all have this flawed design. Wow. How did this ever design ever make it through approval. With sea and summit. Maybe they need to hire me.
I got sick of feeling like a mummy so I decided to change my sleep system. After trying out a few quilts I realized that I really wanted a real sleeping bag but with a wide foot box. Compared with the big Agnes diamond park this bag is roomier, lighter, more comfortable and warmer. This is the only sleeping bag on the market I have found that doesn't make me claustrophobic. Well done sea to summit
I have had this bag for over a year and always take great care of it. The bag is super expensive and a rip off. I would not recommend using this bag in a temperature lower than 1 degree Celsius. Unless you want to freeze 🥶. Even while wearing the recommend thermal base layer. Other wise it's a great bag which is super light weight and will give you enjoyable use for years when used in temperatures above 1 degree Celsius.
I used this bag on a road trip in December with my girlfriend and we loved it! we paired it with a sleeping pad(that was firmly secured to the bag with some sweet straps so the pad didn't end up all wonky) and stayed plenty warm! the colder nights were 20-25 °F and the warmer nights were up to 35-40 °F. it is very light and can compact down smaller than my single big Agnes 0 degree bag but still very warm and cozy. I am 6'3 and my girlfriend is 5' 5 and there was no shortage of space. We took a road trip from Central CA to the Mojave then down to Sedona. Spent a few nights outside of Flagstaff and hiked to the Indian Gardens (campground in the Ground Canyon!) for two nights to Home. The trip took us a little over a week and I couldn't be happier with my choice in ... MoreI used this bag on a road trip in December with my girlfriend and we loved it! we paired it with a sleeping pad(that was firmly secured to the bag with some sweet straps so the pad didn't end up all wonky) and stayed plenty warm! the colder nights were 20-25 °F and the warmer nights were up to 35-40 °F. it is very light and can compact down smaller than my single big Agnes 0 degree bag but still very warm and cozy. I am 6'3 and my girlfriend is 5' 5 and there was no shortage of space. We took a road trip from Central CA to the Mojave then down to Sedona. Spent a few nights outside of Flagstaff and hiked to the Indian Gardens (campground in the Ground Canyon!) for two nights to Home. The trip took us a little over a week and I couldn't be happier with my choice in this sleeping bag.
I love this bag. I had a mummy bag and never felt comfortable and usually would use at as more of a blanket. I then bought a Katabatic gear quilt but that still felt really tight especially in the foot box. Finically I found this and couldn't be happier. The bag is roomy enough that I actually can zip it up. I like the fact the you can add a quilt to make it a winter bag. I like this better than the big Agnes diamond park series since it is much lighter, more compressible and made of higher quality materials. The built in pad attachment system works well with my 25" pad.
I am a warm, side sleeper and therefore tend to get claustrophobic in most sleeping bags. I've tried rectangular bags and also the Nemo spoon bags, but this is by far the most comfortable and roomiest sleeping bag I've ever slept in. If you run cold, I can see the access space possibly being an issue on really cold nights, but that can be solved with some base layers and socks. It also doesn't pack down super small, but this is not a bag for ultra-light backpackers anyway.Perks:- There is just so much room to roll around and bend my elbow and knees in.- Side zippers can turn the bag into a quilt. Footbox zipper can be opened to regulate heat.-
I am 5'4" and fluffy, at the hips im about 58 inches plus the two dogs that would like to share the warmth, which makes finding a sleep system difficult. THANK GOODNESS I found this sleeping bag! It is large enough for me and a medium sized pup, it has zippers everywhere and the top can come off completely so when its warmer I dont have to have too much sleeping bag and it can act more like a quilt. Oh yeah the warmth factor is perfectly spot on. I've been down to lower 30's and warm without my liner. So happy that my money went to such a great investment!!!! Highly reconmend. It packs down decently for being larger, im very happy. The cons are its kinda hard at times to zip up due to the lots of fabric, since its a larger bag but once it gets pulled a bit tight it ... MoreI am 5'4" and fluffy, at the hips im about 58 inches plus the two dogs that would like to share the warmth, which makes finding a sleep system difficult. THANK GOODNESS I found this sleeping bag! It is large enough for me and a medium sized pup, it has zippers everywhere and the top can come off completely so when its warmer I dont have to have too much sleeping bag and it can act more like a quilt. Oh yeah the warmth factor is perfectly spot on. I've been down to lower 30's and warm without my liner. So happy that my money went to such a great investment!!!! Highly reconmend. It packs down decently for being larger, im very happy. The cons are its kinda hard at times to zip up due to the lots of fabric, since its a larger bag but once it gets pulled a bit tight it zips up easily. Just asked the boyfriend any negatives he's heard me say and that he has and he says none and hasn't heard me complain once. I am super happy!!
I needed a new sleeping bag with three non-negotiable features: non-constrictive (wider), with a right-side zip, and with some fill on the underside. I have wide shoulders despite only being 5'8" and narrow mummy bags give me no room to move or regulate heat if I need to unzip as I spill out completely. I am right handed but prefer a right zip (it annoys me that many companies only offer a left zip in mens bags). My previous bag from a different company didn't have any down in the underside portion due to their sleep system, which I found to be very weird feeling and cold, even with a high R value pad. So, the Sea to Summit Amplitude looked to solve those problems while giving amazing flexibility to zip however I want on both sides. I am very satisfied with the ... MoreI needed a new sleeping bag with three non-negotiable features: non-constrictive (wider), with a right-side zip, and with some fill on the underside. I have wide shoulders despite only being 5'8" and narrow mummy bags give me no room to move or regulate heat if I need to unzip as I spill out completely. I am right handed but prefer a right zip (it annoys me that many companies only offer a left zip in mens bags). My previous bag from a different company didn't have any down in the underside portion due to their sleep system, which I found to be very weird feeling and cold, even with a high R value pad. So, the Sea to Summit Amplitude looked to solve those problems while giving amazing flexibility to zip however I want on both sides. I am very satisfied with the materials and warmth of the bag. In fact, this 25 degree bag was a better performer than my previous 15 degree bag and that is with the extra room. I appreciate the zipping options so I can have my desired entry and exit from the right side. I also like that they took the time to ensure that zippers would not get caught on material (my previous bag, which was supposed to be an easy zipper always jammed and was annoying). But, there is one major design flaw that keeps this from getting a perfect five stars, and I think it's a big deal. When they list the circumfrance, the bag appears to be plenty wide for its class. However, this is misleading as the zippers are not at the extremes of the measurements, but are closer to each other, similar to a regular mummy bag. I think they did this for more secure attachement of the pad straps but I really really really wish they didn't. If you move during the night you will feel the zippers directly under you or if you utilize the extra room to spread your legs, you will feel the zippers. That is super annoying. If Sea to Summit ever updates this bag I would strongly advise them to move the zippers to the extreme edges. So, keep this in mind when buying. Yes, you are getting a lot of extra room but the zipper position is not ideal. Otherwise, it's a well built, warm, modular bag that can still stuff down if needed.
I am a side sleeper and am restless with tossing and turning through the night. I'm also claustrophobic and mummy bags with one zipper often times ends up under me with no way to escape. i spent two months researching the perfect bag. this bag is so roomy, i can nearly do cartwheels inside it. having zippers on both sides with foot box venting is genius. the last sleeping bag I'll ever purchase. the last thing anyone wants after a long day on the river is a bad night 's sleep. this sleeping bag changed all that. extremely satisfied and big time impressed with this bag and feeling proud of making a sound purchasing decision.
| Snowys Comfort Rating | −8 °C |
| Lower Limit | −15 °C |
| Shape | Contoured Rectangular | Ultra−wide Circumference |
| Fill Ratio Top/Bottom | 60/40 |
| Max. User Height | 183 cm |
