Garmin 310XT

The 310XT watch features a built-in GPS receiver and an optional heart-rate monitor. It is waterproof to 50 meters, which means it can take part in the swimming portion of a triathlon. This newer model has improved calorie consumption measurement software as well as a “virtual partner,” a program that simulates running with — or against — a partner of similar fitness and speed.

The watch can support exercise information wirelessly to your computer, giving you to transfer workouts on a Mac or PC. A built-in technology captures your location even when you’re not in sight of a GPS satellite, ensuring an accurate measurement while running under trees or between skyscrapers. The 310XT, which should be available this summer, will cost $350 ($400 with heart monitor).