The depths below hold as many potential mysteries as the skies above, yet relatively few have explorer this story-telling avenue in comics.
Previously we considered the lands of Skartaris and Mikishawm, and the men who journeyed there, Travis Morgan the Warlord and Mark Lansing soldier of fortune. There were others who proceeded them and perhaps encountered these same lands.
Famous spelunker Cave Carson recruited fellow explorers Bulldozer Smith and Christie Madison to travel with him to the depths below, guided on their journey in his revolutionary digging machine into various adventures. Later they acquired Johnny Blake to round out their team. After eight documented, Carson's squad met other notables of Earth-One including Superman and the team they'd later join, the Forgotten Heroes...then pretty much forgotten completely!
Cotton Carver himself was an explorer, eventually stumbling upon a subterranean world shortly before his contemporary Lansing traveled there as well. Soon Carver was joined by Deela, Red Mike and Jim Bent throughout the course of his twenty adventures (documented in Adventure Comics in the early 1940's) in this strange new world below. As he fought in the same pages alongside Earth-Two's finest forgotten heroes Hourman, Sandman and Starman, its logical that he was originally from their world as well.