A basil is the most surefire way, since they're immune to the stun and dismount.
If you're more daring, but stuck in scuba gear, armor on your head, gloves and legs and a good pike will save you in most situations unless you're in a cave with a bunch of level 270 jellies and eels.
Crossbow or longneck from afar is a safer bet, if you have a good shot!