There's lots of acreage for hiking in Glacier Bay National Park and Preserve, but just four marked trails, and they're all located near Bartlett Cove.

Hiking the Forest Loop Trail, Glacier Bay National Park and Preserve / NPS
Hikes featured in the Traveler:
The Forest Loop Trail
Most visitors to Glacier Bay never set foot on land, getting a part-day glimpse of the area's stunning scenery from the deck of a cruise ship. Others spend a little longer during an all-day excursion that begins and ends with a flight from Juneau.
If you're one of the visitors fortunate enough to spend a little more time in this remarkable chunk of Alaska, a different view of the park that doesn't include any glaciers or time on the water is available on a short, easy walk near the park's visitor center and lodge at Bartlett Cove. This trail is a great choice if you've taken the full-day boat tour in the park, and have a little time before dinner at the lodge.
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Other Hikes
Here's a rundown on the other three hikes, courtesy of the staff at Glacier Bay:
Bartlett River Trail: Distance: 4 miles (6.4 km) round-trip/Time: 4-5 hours. This trail meanders along an intertidal lagoon and through the spruce/hemlock forest before emerging and ending at the Bartlett River estuary. Watch for coyotes, moose, bear and river otter along the beach. Ducks, geese and other water birds concentrate in the intertidal area during migrations and molting. Salmon run up the river in the latter part of the summer, which attracts hungry harbor seals.
Bartlett Lake Trail: Distance: 8 miles (12.9 km) round-trip/Time: 7-8 hours. Begin walking on the Bartlett River Trail. In about ¼ of a mile (.4 km) down the trail at a signpost, the lake trail will branch off and begin to climb the moraine. This trail is less maintained than the other trails so use caution to not lose the route. The chatter of red squirrels will accompany you as you wind your way over and around moss-covered boulders and lichen-covered trees before reaching the shores of Bartlett Lake. During this full-day journey, you may be richly rewarded in solitude and the perhaps even the call of loons. Bring water, lunch and raingear.
Beach Trail: Distance: 1 mile (1.6 km) / Time: 30 minutes-1 hour. The long stretch of shoreline south of the docks allows for a pleasant stroll. Low tide reveals a myriad of intertidal life. (Please walk carefully!) It’s a terrific place to see land, shore and sea birds. Ask a park ranger for a free tide schedule.