The maintained trail descends from the terminal moraine left by glaciers during the last ice age, then comes to an end at Mud Bay (part of Russell Fiord), although you can continue walking off-trail along the shore.
You may spot a ring of dead trees at the shore. They are the result of the Hubbard Glacier blocking off the fjord in 1986 and again in 2002, temporarily turning it into a lake and causing water levels to rise significantly until the glacier "dam" burst, letting the accumulated water run out to the sea.