Turnagain Arm Tidal Bore Earthcache — Geocache of the Week

by NorthWes
Alaska, United States
N 60° 55.688 W 149° 20.845

f4357d23-742a-4eef-86be-38b3030f2b0dIt was almost 11 years ago, but geocacher and HQ employee Prying Pandora remembers the moment well.

Prying Pandora was with CENT5, also visiting Alaska on a geocaching trip, and NorthWes, a local Alaskan and geocacher who was their tour guide for the day. As they drove along the dramatically scenic Seward Highway in a rented minivan, they took in the never-ending range of snowcapped peaks, and fjords filling with and spilling out water.

Suddenly there came a cry from the back of the car.


It was NorthWes, who had caught sight of the phenomenon that his EarthCache, GCN6YV, describes. The van immediately stopped, everybody piled out (some more or less confused as to what was happening) and NorthWes explained what they were seeing.

Later, in her log, Prying Pandora wrote, “What a totally cool thing to witness, and unbelievable luck to have caught it!”

You see, this EarthCache is all about a bore, but it’s not boring.

Turnagain Arm is a waterway off the Cook Inlet in the Gulf of Alaska. The Arm’s unique combination of topography and tidal activity results in the geological feature that’s at the heart of this EarthCache: the tidal bore.


Before you say, “No, you’re a tidal bore!” let’s talk about what ‘tidal bore’ means. Basically, it’s a wave—a very, very special wave. It’s the individual large wave caused by a sudden influx of water rushing into a narrow, shallow inlet that’s still draining water from the previous tide. The rush of water coming into the inlet runs right into the draining water going out in the opposite direction, and boom!


Making it to the right spot in time to catch that wave’s journey through Turnagain Arm (and take a photo of it) is the task prescribed in this Geocache of the Week.

Possibly the only EarthCache in which you might be photo-bombed by surfers.
A close-up of the tidal bore.
Alaska, the beautiful!

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Alex is a Community Volunteer Support Coordinator at Geocaching HQ. When things get crazy, she sends in the big puns.