Sound travels faster in water than air because it moves as a result of particles bumping into each other; water particles are much closer together than air. Liquid molecules have substantially less energy than gas molecules, which means they are closer together.
A sound is a wave that is transferred by particles. Since particles are spread so far apart in gas, it takes longer for them to bump into each other and transport the sound. In water, however, particles are right next to each other. This is why sound can travel over 3,280 feet per second in water, but only about 1,083 feet per second in air.