The Lone Island Coliseum can be found by falling into the Eventide Island Chasm.

Coliseum Location

The Lone Island Coliseum is located in the part of the Depths that can only be reached via the chasm on Eventide Island in southeast Hyrule.

Coliseum Combatants

Approach the treasure chest in the Lone Island Coliseum and you will battle Bokoblins, Blue Bokoblins, Black Bokoblins, a Silver Bokoblin, then a group of all four types.

Coliseum Reward

The reward for defeating all of the Lone Island Coliseum enemies is Midna's Helmet.