You can breathe air and water. In addition you have a swim speed equal to your walk speed + 10 ft.

As a Bonus Action on your turn you can expend up to a number of hit dice equal to your Constitution modifier (minimum of one) to regain hit points equal to the number you rolled. You can use this trait a number of times equal to your proficiency bonus, regaining all expended uses on a Short or Long rest.

Losing or badly injuring a limb or non-vital organ does not kill you, and it regrows over the course of 1d4 weeks. In addition losing or badly injuring a vital organ or piece of your brain (not the whole thing) does not kill you and regrows over the course of 1d4 weeks, but you have vulnerability to Bludgeoning, Piercing, and Slashing damage as well as disadvantage on Intelligence based checks as you are essentially drugged on hormones while your body tries to recover for the next 1d4 days. Healing hit points by using your Regeneration trait reduces the time it takes for any current regrowing body parts to regrow by 4d6 hours.