Garmin’s Forerunner 310XT ($250) offers a pretty powerful set of features in a watch designed for water sports. For starters, it’s waterproof to 165 feet, which should be adequate. It has GPS, so it tracks your location, speed, distance, and more. It watches your calorie burn. And with an optional heart strap it will keep track of your heart rate as well. It has all the usual watch features—even a backlighted display—and can talk wirelessly to a PC or Mac.