Yup. Some more than others. Some need to be in water 90% of the time and others split their time but they all require water as many of them will eat, breed, shed, and mate in water.
Amphibians evolved from fishes and aquatic creatures, so they basically need water in, a moist or muddy environment to survive. It helps to keep their skin moist, and it helps them to breathe better. They like to use both their lung capacity to breathe on land and their gills capacity to breathe underwater. So it is best to place them in such environments where they can get the best of both air and water.