An atmospheric diving suit is like a really cool and heavy suit that divers wear when they want to go really deep in the ocean.
This suit weighs about 1,000 pounds and is made of strong materials that can withstand the pressure of the water when the divers go deep. It also has special joints that allow the divers to move around and do things, like working on a big ship or exploring the ocean floor.
The suit is also filled with air, which helps the divers breathe even though they are deep underwater. The air flows through hoses that are connected to tanks on the surface, where people make sure the divers always have enough air to breathe.
Because the suit is so heavy, the divers can't swim around like they do on the surface of the water. Instead, they walk around using big boots that help them stay balanced and stable.
It's really important that the divers are very careful when they wear this suit because they are completely cut off from the outside world and if anything were to go wrong, they wouldn't be able to come up for air quickly. That's why only specially trained and experienced divers get to use an atmospheric diving suit.