You are sent to that canyon on a mission "Don't Copy That Floppy", given by C3n50r in The Washburne Refinery after/during "Whoops".
This arena is where Hyperius the Invincible stands around all day waiting for challengers. You will receieve a quest for this boss after beating.
message board topic titled "WHOOPS Washburne Refinery". to it, long circle going to the east, then north, then back to the last piece.
the Xbox , a GameFAQs message board topic titled "Cant get to last poly kryten in washburn refinery". It'll loop back on itself eventually.
Whoops is the seventh story mission in Captain Scarlett and Her Pirate's Booty. There are four globs of poly-kryten scattered throughout Washburne Refinery, laid this area is a one-way jump, the return path being too high to leap back up.
Washburne Refinery is a location in Captain Scarlett and Her Pirate's Booty DLC in Borderlands 2. It is used by the Hyperion Corporation as an Eridium refinery.