Those burn the same fuel...

Boats aren't constrained by weight like planes are. You could put any amount of batteries on a boat and get it to float and move on water. They can also be moved by wind. I may be wrong, but I also thought there existed some nuclear powered boats.

Boats are very much so.

The largest container ships consume 250 tons of heavy fuel oil per day, they haul up to 15k containers and are at sea for months.

Filling a ship with enough battery power to replace that isn't remotely feasible. Just charging it at port would be an insane undertaking.

It's a truly crazy amount of energy.

We've had nuclear powered ships for 50+ years (even some civilians ones!). It seems like the problem is making them commercially viable. Maybe they would be if their competitors had to pay for the negative externalities of burning 250 tons of fuel per day?

Boats do, but trains are mostly electric.

Not in the US, their mostly diesel here

Before that. Walking.