Sea Scholar's Lantern

The Sea Scholar's Lantern is an item lighting up the area in front of you. It does not require any fuel, making it an excellent alternative to torches. It can be used like a staff as a secondary to a single handed object (sword, pickaxe, fishing rod, daggers and bombs, etc...).

Source
The Sea Scholar's Lantern can be bought from a Sea Scholar after the Poem from a Pirate quest is completed.