What's under the water off the Navy Pier? Trash, as it turns out.

That was the inescapable conclusion from the photos an underwater robot brought back from the bottom of the Navy on Wednesday. Beneath the surface, it's pretty disgusting.

The mechanical explorer found lots of empty bottles and discarded cups.

But there's good news. The people who brought their Remotely Operated Robot to the Navy Yard on Wednesday, the Rozalia Project, say cleaning up our oceans, lakes and ponds starts simply. Just pick up the trash from the land, where 80 percent of marine debris comes from.

"All that stuff on the land now will go into the water or find its way into a storm drain," said Rebecca Inver Moffa, science and education coordinator for the project.

Kids from Courageous Sailing, 13 of them, did their part keeping more junk from getting into the water by picking up 800 pieces of trash on Wednesday, according to Rozalia Project's founder and director Rachael Miller. So far this year, the project has removed 175,000 pieces of trash from New England waters.

Miller's team fascinated residents who visited the dock to see the live feed of images from the robot trolling the bottom of the Pond. They also got to get a load of the trash haul.

The Rozalia Project goes to waterways all over New England. On Thursday they visited Community Boating on the Charles River. Later on Wednesday, they explored Jamaica Pond.

Want to clean up local waters? It's easy. Take a bag with you on your walks and catch items before they get in the water.