The most basal of marine cetaceans, ambulocetids lived in shallow near-shore environments such as estuaries and bays, but were still dependent on freshwater during some stage of their life.
Ambulocetus and Gandakasia primarily ate terrestrial prey, while a combination of low oxygene isotope and high carbon isotope values suggests that Himalayacetus consumed freshwater but ate marine prey, thus that it foraged in a marine environment but returned to freshwater to drink [REF].