A group of turtles is called a "bale." Many people use the term "herd" to refer to a group of turtles. No matter what species, all turtles belong to the order Testudines.
Pond and river turtles and the like spend their lives in or near bodies of water and are dependent on them. Tortoises are turtles belonging to a subgroup called Testudinidae. Tortoises differ from regular turtles in that they only go in or near water to drink or bathe. The largest turtles live on the Galapagos Islands in the Indian Ocean. These large tortoises weigh as much as 800 pounds.