How do I get my pally to swim under water when dead?

Im so aggravated. I'm trying to reach my body in the Sunken Temple but my pally wont swim under water at the entrance so i cant get in... I use a mac with a trackpad but i put batteries in my mac mouse to try all the different ways i looked up online to swim but nothing is working... Im missing the whole run and I was so close to leveling. Please help asap