Tortoises are actually not able to swim. They belong to the taxonomic order called chelonia. This order includes tortoises, turtles and terrapins. All three are cold-blooded, have scales and reproduce by laying eggs. Only two of these species, turtles and terrapins, are able to swim. Tortoises may enjoy wading in very shallow water, but they do not have limbs or bodies built for swimming.
Tortoises live on land and are herbivores, eating grasses or very short shrubs. Pet tortoises are usually fed with a diet of lettuce, alfalfa, clover and possibly some fruit. Tortoises can live as long or longer than a human, with recorded tortoise life spans of up to 176 years. Their hard shells have a high, rounded dome, and they have legs that are columnar in shape like an elephant's. Their round, stubby feet allow them to dig shallow burrows in the ground in which they can lay eggs or cool themselves in warmer weather. Tortoises do enter water to drink or to bathe, but they cannot swim and will drown if put into deep water. For smaller pet tortoises, it's important to provide a habitat that includes water for drinking and bathing, but not water that is not so deep that the tortoise can't stand. Young children should be supervised around tortoises to make sure they do not put them in a bathtub, toilet, or sink to see if they can swim.
The turtle spends most of its time in the water. While most turtles do come out of the water to bask in the sun on logs or to lay eggs, some spend most or all of their time swimming. Turtles generally have webbed feet that make it easier for them to swim, and sea turtles have bodies that are specially shaped for swimming and elongated feet that form flippers. Sea turtles do not usually leave the ocean, except when females come to shore to lay their eggs. When these eggs hatch, baby sea turtles painstakingly make the journey back into the ocean, using their flippers to push themselves through the sand. Freshwater turtles generally enter a state of hibernation called torpor, specific to cold-blooded reptiles. They do this by digging themselves into mud until the warmer weather of spring arrives. Pet turtles may require an aquatic environment, and many pet owners use fish tanks to house them. Some turtle varieties enjoy having a large rock or branch on which to bask under their reptile light.