Would humans live longer living undersea?(in an air chamber)?

I wa slooking at axolotl's .. that live in their usual larval state for 10-15 or even longer years but if they are iodine induced to metamorph they live a hell of alot less long .. 5 years if lucky. I also read that some aquatic animals live longer than many animals land dwelling (if not eaten by something) maybe related to less radiation making it underwater. anyone that can confirm this with any studies? also read that "aliens" prefer to live in deep bodies of water.. I wonder why..