Mountain biking around the Arenal Volcano in Costa Rica for this Boston Globe story, my buddy Jeff and I crossed several streams.  It was an exhilarating ride, except for the puddle of water sloshing through our sneakers the rest of the day.  Thankfully, we met a couple from Boulder, Colorado, who highly recommended the water shoes they were wearing, Saloman Tech Amphibian Water Shoes.  We immediately went home and purchased several pairs on the REI website (happily discounted to around $50 US) and we've been using them ever since.  They have the shape of a sneaker with a great tread, ideally suited for mountain biking and hiking though water, like our family trek up Dunn's River Falls in Ocho Rios, Jamaica.  Don't get caught with wet sneakers on!