Here is a copy of Captain America #136-April 1971
It is in used condition.
See pics for condition.
THE WORLD BELOW
According to Travis Starnes' Website, it states, "After seeing Captain America drop into a pit, it seems inevitable that the star spangled avenger is dead. Unwilling to give up hope without proof, the Falcon decides to attempt to find his partner. Meanwhile, below the surface, the Mole Man saves both Gorbo and Captain America to learn why they have come to his land."