Turning down promotions because they would interfere with his goal, Brashear went to Washington D.C.’s Experimental Diving Unit in 1970. Using a Titan II mask, and breathing a helium/oxygen mixture, he did saturation dives of 600-1,000 feet.

He was evaluated for five weeks. A candidate either makes it or doesn’t make it. Many don’t. Carl describes what it means to be a Master Diver:

Master diver is a man that’s proficient in all phases of diving.
The highest position that you could hold in the diving
community is master.

After years of dedication, training, frustration, disappointments, and obstacles Carl Brashear’s tenacity was rewarded. He became a Master Diver in June of 1970. He had achieved his goal. His superiors were amazed he had pulled it off. Advising Brashear of the decision to make him a Master Diver, the Commanding Officer gave Carl high praise:

Let me tell you something. If there was a mark that we’d give,
you made the highest mark of any man that ever come through this school to be evaluated for master. You did not make a mistake.

By this time Carl had attained the rank of Senior Chief Boatswain’s Mate (E-8). His fellow black chiefs, who knew how hard he was striving to become a Master Diver, weren’t sure he would make it. Blacks, after all, had never been Master Divers before.

As a Master Diver, Brashear was assigned to the USS Hunley where he had his first experiences diving on nuclear-powered submarines. He also served on the USS Recovery (ARS-43).