A bore tide or tidal bore is a wave formed by the rising tide coming into a funnel-shaped body of water.
The waves in some cases are large enough to be ridden by surfers and whitewater kayakers. Along the Seward Highway
south of Anchorage, waves up to 10 feet high can be seen as they race up Turnagain Arm.
The biggest waves there are formed when the tide range is at least 30 feet and the low tide is at
least -1 feet - the Web sites linked below describe the details.
The NPS has an excellent guide to seeing the largest waves.
Anchorage Tides for Summer 2013
The bore tide should reach Bird Point 2 hrs and 30 minutes after Anchorage low tide. It takes over 5 hours for the bore to travel the length of Turnagain Arm.
Alaska.org has a good guide to seeing the largest waves.
Bore Riders Club
These folks from the UK have posted some excellent information from a surfer/kayaker's perspective.
The Seward Highway
A guide to other attractions along the highway.
Highway to Portage
Sights along the highway, including the bore tide.
Turnagain Arm Beaches
The sandy beaches of Turnagain Arm may look inviting, but they are actually very dangerous.