Underwater Tunnel to the Lighthouse

The Underwater Tunnel to the Lighthouse is a location in the Seaside Kingdom in Super Mario Odyssey. As it would, it is an underwater tunnel to the Lighthouse. Aside from the Checkpoint Flag on top, this is the only way to reach the top of the lighthouse. The opening leading into the tunnel is found north of the lighthouse.

As soon as Mario enters the tunnel, he finds two Cheep Cheeps circling bubbles. Just up ahead, there are menacing Maw-Rays which pop up out of the ground as well as the walls. After the first round of Maw-Rays, there are three regional coins, then a few more. After getting past a few crates and Cheep Cheeps, Mario reaches the Warp Pipe taking him out of the tunnel and onto the lighthouse.

The tunnel is listed in the Seaside Kingdom brochure, where it is described as one of the more dangerous locations, serving as a nest for the eels. The brochure advises caution when exploring and traveling through the tunnel.