Below is a little bit about Deep 6 according to his Wikipedia page:
(the original version of this information can be found by clicking here.)
His real name is Malcolm R. Willoughby, and his rank is that of Navy petty officer 2nd class (Master Diver's rating). Deep Six was born in Baltimore, Maryland.
Deep Six's primary military specialty is diver and his secondary military specialty is small craft pilot/motorized. He likes to be alone, preferably down in the ocean depths. He was one of the 12 out of 50 applicants who passed the strict requirements for the position of the Joe Team diver; eight more washed out in the practical application testing, and of the four finalists Deep Six could hold his breath the longest.
This is what his Wikipedia page had to say regarding toys of Deep 6:
Deep Six was first released as an action figure in 1984, packaged with the S.H.A.R.C.vehicle. A new version of Deep Six was released in 1989, which was more mobile and poseable than his original figure. That version was recolored and released as a mail-away exclusive in 1993. A new version of Deep Six was also released as part of the Eco-Warriors line in 1992, which came with a pet dolphin named "Finback".
A version of Deep Six was released in 2009 as part of the "Rise of Cobra" line, despite not appearing in the film of the same name.
This is what his Wikipedia page had to say regarding comits of Deep 6:
In the Marvel Comics G.I. Joe series, he first appeared in G.I. Joe: A Real American Hero #25 (July 1984). Several fellow Joes note how Deep Six keeps to himself. Deep-Six then battles Firefly and Wild Weasel in the Florida Everglades in defense of other Joes.
He next appears in G.I. Joe: A Real American Hero #33 (March 1985) when he is assigned to help decorate for an upcoming party. He escapes any actual work when a coincidence allows other Joes to bring back a party van filled with balloons.
Deep-Six is injured as part of a Joe battle against Cobra forces in the Gulf of Mexico.