Last Saturday morning at 9 a.m., I plunged into Lake Pend Oreille with 668 other people and swam 1.76 miles, about half of it under the shadow of the long bridge that carries U.S. Highway 95 into Sandpoint, Idaho, for the 20th anniversary of the Long Bridge Swim.
Waves chopped at my face with every attempted breath – the wind was up – but I finished the swim in 72 minutes (the overall female winner, a woman in my age-group, swam the distance in just under 44 minutes). The sun-warmed water was the perfect temperature, and so was the post-race ice cream.
When I got home, I did some research on the lake. It’s one of the biggest lakes in Idaho, and the fifth deepest lake in the U.S., with a maximum depth of about 1,150 feet.
And the U.S. Navy operates a submarine-testing station there.
Evidently the combination of the depth of the lake and its relatively quiet location make it the optimum location for research on the acoustics of operating submarines. According to the official website of the Acoustic Research Detachment, “Lake Pend Oreille provides a deep (1150 ft), quiet body of water where a free-field ocean-like environment is available without the attendant problems and costs of open ocean operations.”
Recent research projects conducted at the site include the field-testing of a novel navigation system for autonomous underwater vehicles – basically underwater drones that are programmed to operate on their own once they’ve been launched – and the development of a new way to produce underwater sound waves for use in experiments and surveys that’s more environmentally friendly than other methods.
I didn’t see any model submarines or autonomous underwater vehicles during my swim (not surprising, since the Navy facility is located 26 miles south of Sandpoint in Bayview, Idaho), but I did see a lot of determined people, fighting the waves toward the finish line.
Wolbrecht E, Anderson M, Canning J, Edwards D, Frenzel J, et al. (2013) Field testing of moving short-baseline navigation for autonomous underwater vehicles using synchronized acoustic messaging. Journal of Field Robotics 30(4): 519-535. doi: 10.1002/rob.21460
McNeese AR, Wilson PS, Sagers JD, Knobles DP. (2014). An impulsive source with variable output and stable bandwidth for underwater acoustic experiments. Journal of the Acoustical Society of America 136 (EL8). http://dx.doi.org/10.1121/1.4879665