It's always fascinating to read more about New Hampshire's history, and this writer recently learned of a harrowing underwater rescue that happened in Portsmouth over 80 years ago.

According to the Naval History and Heritage Command website, it all started on May 23, 1939, when the USS Squalus "suffered a catastrophic valve failure during a test dive off the Isle of Shoals." As a result, the submarine began to flood, eventually sinking 240 feet down to the ocean floor. The National Medal of Honor Museum explained that 26 men were lost as a result of the flooding, while 33 others remained alive "in the forward compartments". Could you imagine how terrifying that must've been?

The New England Historical Society described the subsequent rescue efforts as a harrowing "39-hour ordeal." According to the NHHC, it was another submarine which eventually "lowered the newly developed McCann rescue chamber--a revised version of a diving bell...over the next 13 hours, all 33 survivors were rescued from the stricken submarine." It wasn't until months later in September when the USS Squalus itself was pulled out of the water.

Here are some pictures from the disaster, starting with the Squalus itself prior to the sinking:

Naval History and Heritage Command
Naval History and Heritage Command
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This image, taken in August, shows the "blowing of salvage pontoons to lift Squalus off the sea bottom."

Naval History and Heritage Command
Naval History and Heritage Command
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Finally, here's "the divers closing valves in salvage pontoons" once the submarine had been lifted from the ocean floor.

Naval History and Heritage Command
Naval History and Heritage Command
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Speaking of New Hampshire's history, here are 10 of the most historic restaurants in the Granite State. How many have you visited?

Step Back in Time at These 10 Historic New Hampshire Restaurants

You Can Live in the Historic $3.8M Pickering-Heffenger House in Portsmouth, New Hampshire

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