Question:  Nikolai Mikhaylovich Albov is credited with being the first European explorer to have traveled extensively over an archipelago off the southernmost tip of the South American mainland across what strait?         
Sentence (from "Antarctic Peninsula"): Beneath the ice sheet which covers it, the Antarctic Peninsula consists of a string of bedrock islands; these are separated by deep channels whose bottoms lie at depths considerably below current sea level.
Relevant evidence: No