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.

Viewing Guide
Alaska.org has an excellent 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.

Highway to Portage
Sights along the highway, including the bore tide.

Anchorage Tides for Summer 2009
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.

Turnagain Arm Beaches
The sandy beaches of Turnagain Arm may look inviting, but they are actually very dangerous.