For people who spend time on water activities, a pair of water shoes can provide great comfort and safety. The requirements might differ based on activities. Below shows the key performance considerations
Water shoes should fit snugly wet or dry. Submersion can do a number on the shoe materials. Water shoes need to fit well through repeated cycles of wetting and drying - that means being made of synthetics that don't absorb much water and don't deform significantly when wet. If you plan on spending a lot of time on land with your water shoes, drainage is also key to preventing soggy feet and blisters.
While drainage can be nice, you can usually cool off in the water. Water shoes that prioritize warmth are generally more effective than those that prioritize drainage.
On slick surfaces, friction is key. Almost all water shoes use special rubber that sticks well to rock and other smooth surfaces underwater. Many water shoes achieve good wet traction by using specially formulated sticky rubber (similar to climbing shoes), and some even feature razor-siped outsoles, similar to winter tires.
Flexibility and Sensitivity
Flexible soles help with boat control and swimming, but a stiff sole can be more protective. Some kayakers prefer more flexible shoes that allow them to slip their feet into a narrow cockpit easily. While flexible shoes are great in the boat and open water, they often sacrifice protection that is key for uneven ground.
Flowing water and rough rock can be a shoe-gnashing combination.
Super-specialized shoes are great, but a shoe that can do many things can save you a lot of money. Many water shoes can also work fine as hiking or even running shoes.