CHICAGO (CBS)– A diver was rushed to the hospital in critical condition early Sunday after suffering from decompression sickness.

The Fire Department said around 11:20 a.m. that its crews were heading out into Lake Michigan for a diving accident.

They found the 40-year-old diver in a dive boat 18 miles east of Navy Pier. He was suffering from decompression sickness, also called the bends, which is caused by coming up to the surface too fast.

The fire rescue boat took the diver up to Montrose Harbor. From there, he was rushed several miles to Advocate Lutheran General Hospital in Park Ridge, which has the required hyperbaric chamber to treat him, the Fire Department said.