Possible Clues:

• Platform for one who stands for progress on the surface?
• Get towed behind a motorboat
• Engage in sport and risk a wet trip
• Sort of at risk, we participate in sport
• Summer footwear
• It's hard to do this barefoot
• Item used in aquatic sport
• Travelling on one may involve a wet risk
• Runner or skater performing in Wisconsin
• Travel behind speedboat