A whitewater specific shoe, the Sea to Summit Ultra Flex Bootie is the quintessential shoe for jamming into a low-volume kayak or swimming. The velcro strap wraps around the heel, keeping them secure. Their sock-like fit makes for excellent flexibility. They stick well on hard surfaces but are too minimalist for longer hikes. The neoprene material keeps your feet warm and comfortable when wet. While a great kayak-specific shoe, they don't function well on associated dry land activities.
Sea to Summit Ultra Flex Booties Review
Compare prices at 2 resellers Pros: Very sensitive, good traction, secure for swimming
Cons: Not versatile, lack in support and protection for rough terrain
Manufacturer: Sea to Summit
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Our Analysis and Test Results
The Ultra Flex is a classic neoprene bootie, featuring 3mm neoprene and a sticky rubber outsole. They weigh just above half a pound for a US women's size 8 and fold down small for packing.
The Ultra Flex fits around the foot like a sock, kept secure by a velcro strap that wraps around the heel. While other shoes tested were likely to come off in a swim, we were assured these ones weren't going anywhere.
The neoprene keeps your feet warm in cold water. But given its snug fit, anything more than a pair of wool socks was too thick to wear underneath. The Ultra Flex is the closest thing to sticky bare feet you'll find. Thus, walking on rough terrain is uncomfortable and potentially hazardous. On a boat and in the water, though, is where these shoes are comfiest.
The rubber outsole provides great traction on wet rocks, logs, and navigating a wet raft. This is aided by its flexibility, enabling your foot to follow the natural curvature of the surface.
The Ultra Flex essentially lacks lugs entirely, making them less than ideal for slick soft surfaces like a muddy trail or sandy hike. We found our arches and Achilles straining on these surfaces. That being said, these shoes are purely made to be on the water.
The Ultra Flex isn't meant to be used across a wide variety of activities. It functions well as a boating-specific shoe, and is comfortable and warm for full days on the water. It works well as a boating or swimming shoe, but you'd be unlikely to find us wearing it on a hike given its lack of durability and foot protection.
The neoprene materials provide excellent insulation when wet. Yet this is only up to the ankle, as adding warm layers was difficult.
We barely fit a dry-suited foot into it; a wool sock was as thick of a material as the stretchy neoprene would accept. For truly frigid days, the Ultra Flex doesn't have enough layering capability. For more mid to higher temperatures, the Ultra Flex fits the bill.
The neoprene is glued to two pieces of rubber: the outsole and a smooth reinforcer between the two. The velcro strap seems a bit flimsy, but then again you're unlikely to be yarding on the strap as much as you might with other shoes.
The neoprene is relatively thin, so it's subject to punctures or abrasions. For short walks up to the surf wave and takeout and promptly into a kayak, the Ultra Flex is fine. For navigating rougher terrain, the shoes will be worn down much more quickly than heftier shoes.
The Ultra Flex Bootie is the most sensitive shoe we tested. With no insole and a thin outside, you'll feel every bump and inconsistency. These shoes are ideal for swimming and playboating, given their low profile and neoprene construction, but are almost too sensitive for walking on land, unless you're used to being barefoot entirely.
For the playboater or swimmer, these shoes are a great value. It provides decent warmth and traction for navigating short hikes or portages. They lack in durability, but you won't break the bank just getting another pair if you put a hole in the neoprene.
The Sea to Summit Ultra Flex Bootie thrives as a boating-specific shoe but lacks function in other areas. The 3mm neoprene keeps your feet warm in cold water but is difficult to pair with socks or a drysuit. It's made to be flexible, sensitive, and low-profile, and for this, it excels. While you wouldn't want these shoes if you plan on doing long portages or scouts, it will do the job scaling a boat ramp at the put-in and take-out.
— Monica Nigon