Haunted said:Bring a Fire weapon. Fish him out first (frog, fishing spot in 4) to get some easy hits in. Stay on his sides taking aim at his tail because most of his attacks consist of lunging straight ahead, or swiping behind him with the tail.
If he inflates himself, he adds a roll-over attack to his arsenal which can do some nasty damage. Learn the tell for this one to avoid getting squashed repeatedly.
If you have to fight him underwater (not preferable, but sometimes you have little choice), try to stay above and to the side of him attacking the lantern (which is his weakest spot, so you will do the most damage there). Water is his element, so try to play it safe and get only one or two hits in before getting ready to dodge. If he burrows under, that's perfect for you. Either sonic bomb him to get more free hits, or follow the slight "bulge" in the ground to easily anticipate where he'll emerge.
He can be a bit of a pain when you have to fight him underwater and in a narrow confine (like area 3), I prefer to fight him on land in 1 or 4. 8 is fine as well because you have better visibility. Hope that helps!
Thanks for the tips, I will try them out tonight