For Surfing
For surfing (and also windsurfing, kitesurfing and other such sports) bootees are typically worn where the weather is so cold that the surfer would lose some degree of functionality in his feet. The bootee should be thin enough that it can be worn with the leg of a wetsuit pulled over it. Another concern is that the bootee should not restrict the ability of the surfer to grip the board with the toes in the desired manner. Split toe bootees allow for some further functionality in this respect.
Reef walkers are small bootees that are only as high as the ankle and generally are only between 2 and 3.5mm thick. These bootees are designed to allow surfers to get out to waves that break at coral reefs or at rocky beaches.
Read more about this topic: Wetsuit Boots