For 10 points, what is this strait that was surveyed by Captain Robert Fitzroy and named after his ship, which also carried Charles Darwin?
Picton Island marks the eastern entrance of this body of water, which is two hundred and  forty kilometres long, splitting into two branches around Gordon Island near its western  end. Settlements along its north side include Yendegaia and Ushuaia, and on its south side, Puerto Williams and Puerto Navarino. Its eastern half separates Chile from Argentina, and it runs along the southern edge of the main island of Tierra del Fuego. For 10 points, what is this strait that was surveyed by Captain Robert Fitzroy and named after his ship, which also carried Charles Darwin?
Picton Island marks the eastern entrance of this body of water, which is two hundred and  forty kilometres long, splitting into two branches around Gordon Island near its western  end.
Beagle Channel ( or  Canal Beagle)