You can't safely go through them with anything other than a Knarr without it breaking and it serves as the entrance to a sort of end game instance. Have it damage the Knarr upon entering and exiting to dissuade as much as possible from abuse but obviously don't let it do over 50% damage to the boat because the groups obviously going to need to go back out the same way.
Make it challenging and rewarding for groups to give them a bit more to do late game.
Meteors are already good for encouraging group PvP. Now let's add an even more dangerous and perilous end game group focused challenge.
1. Oceans are dangerous as fuck to be running into other groups and battling
2. Groups are going to be in an dungeon/den/instance area with all of the same dangers that those usually bring like no hearthing etc etc.
3. Dangerous as fuck enemies within that are no joke.
So it'll work like this
>Travel to the Maelstrom via Knarr
>Enter Maelstrom
>Puts you and your group aboard the Knarr in an underground cave with a small body of water near the entrance that your group can used to disembark from the Knarr to enter the dungeon properly
>Plays out like a regular dungeon after that, you fight ON LAND in the dungeon, not on any boats, your Knarr is docked at the entrance.
Imagine multiple different big villages kitting themselves out in their best gear, boarding their Knarrs and all heading towards this area.
It adds a new dynamic to the game because we're so used to oceans being kinda worthless outside of shit like whale hunting and Knarr's feel like they have less use than Snekkja's despite being the direct upgrade.
I think it'd be cool as fuck. Yes it's dangerous as fuck because people won't be pvping how they're used to pvping, it's not gonna be on regular ass open ground like when a meteor drops and groups just chase each other around doing their usual thing. No, rather this carries with it a very real chance of dying because of the ocean and because of the dungeon. Not every group is going to be able to take part in something like this and that includes myself, this is going to be something the biggest baddest villages on the server will fight over or even ally up for in some cases.
I always see the big villages complaining about not being able to fight each other. Be it because sieges are too difficult or because there's no incentive for one village to come out and fight the other. This provides an incentive. Have the reward for this dungeon be big enough that people aren't going to want their enemies to get it because it'll propel them further into the lead. Let people be diplomatic and form alliances with other smaller villages to get more people to go with them to put the advantage in their favour.

This is the end game content I long to see in a game like this. Imagine the videos of 2 colossal alliances fighting it out for the ultimate prize. This is what the game is missing.
THE ONE PIECE..... IS REAL and it exists within THE MAELSTROM
