Which animal can swim underwater walk on land and has a big bite?

I'm pretty sure that's an Alligator

Answer is the salt water crocodile.

Alligator has small legs with webbed feet. This enables it to swim under the water and walk on the land. Crocodiles also have a similar body structure like the alligators. They can also swim and walk. The alligator has a huge jaw with sharp teeth that can deliver a bite that damages internal organs of its prey. But there is a difference between the bite forces of alligator and crocodile, the crocodiles are bigger than the alligators, their jaws can deliver much more powerful bite than the alligators.