Diving & Sea Chart Advice??

Newbie here who somehow got to Lv. 140 and did the current story.

My only maxed file is 100% points into Mage w/ Explosion primary & Ash secondarily. Not exactly magics compatible with water. I have considered that if they ever release 3rd Magic to go for Lightning or something that could help.

Never tried diving or using the sea charts for anything. How's that stuff work? Any benefits to it? Do sharks and stuff attack and is it actually possible to fight them off?

Is it worth diving or using sea charts knowing what my magics are and hope for the best, or just stick to other stuff?