Like Visiting an Alien Landscape: Lake Huron Sinkholes

If you ever get the urge to explore underwater sinkholes, here's where you should go: Alpena, where there are a handful of holes in Lake Huron.

Why are there so many sinkholes in Lake Huron?

Thanks to Alpena's unique karst geology, many sinkholes and crevasses have formed on the lake floor, most with venting groundwater. Thanks to the constant flow of groundwater that contains a high number of sulfates and very little oxygen, white and purple microbial mats form in layers on the lake floor.

The deepest sinkhole point is 290 feet, and no sunlight can reach the bottom. Mixed with hardly any oxygen, bizarre objects form like giant slimy worms and tiny pyramids that make the lake floor appear as if you are on another planet. But you are definitely in a land of alien nightmares, as you will see in the photo galleries below.