Commissioned in early 1939, the USS Squalus was the 11th of the new Sargo class of submarines, which were named for fighting fish. This new breed of underwater boat was 310 feet long and 27 feet wide, larger than any previous class. She had improved surface and underwater speed and extended range, which enabled the sub to keep up with fleet surface ships up to a speed of 16 knots. She had seven watertight compartments, plus a conning tower and amenities such as flush toilets, air conditioning and cold food storage.
At 7:30 a.m. on May 23, 1939, the Squalus left the Portsmouth Navy Yard located along the Piscataqua River in New Hampshire. She was underway for her 19th test dive under the command of Lieutenant Oliver Naquin. Before a submarine could qualify for the operational fleet, it was required to pass a series of trials. On this day, a crew of 59 was on board, comprised of five officers, 51 enlisted men and three civilian inspectors. The point of the day's test was to complete an emergency dive while cruising at 16 knots, diving to 50 feet within 60 seconds in order to avoid enemy attack.
The spot chosen for the dive, southeast of the Isles of Shoals off the coast of New Hampshire, averaged a depth of 250 feet. As the submarine neared the designated point, her location and estimated submersion time were radioed to the Portsmouth Navy Yard. At 8:35 a.m., according to the deck log, Naquin order the crew to rig for a dive. Shortly thereafter, he ordered the dive to commence.
The Squalus sank at around 8:45AM. She settled on the bottom without a list, but with the bow raised by 11 degrees. The depth was 243 feet, and the water temperature was just a few degrees above freezing.
As the ship had taken on water during the dive, the well-trained submariners on board had sealed shut each watertight compartment. On the bottom, the first problem were sprays of water and oil, which were stopped by quickly shutting many valves and securing loose fittings. Only the dim light of a few battle lanterns staved off complete darkness.
Determining who was alive and each individual's location was the next priority. Of the 59 people who sailed that morning, 23 were in the control room and 10 in the forward torpedo room. It was likely that everyone in the after battery room and both engine rooms had died. No contact was made with the after torpedo room. The possibility of survivors there remained, but it was a dim hope.
Five people were moved forward, where it was dryer but colder than in the control room. Saltwater was leaking into the forward battery, creating an even more dangerous situation. If it mixed with the battery acid, chlorine gas could form, or it could short the cells and start a fire. This meant that the forward battery compartment, which was located between the two occupied spaces, would have to be left vacant. The control room had a foot of oil and water at its after bulkhead. The pump room beneath it had a slow leak.
A telephone buoy, attached to Squalus by the communication cable, was released and surfaced soon after the sinking. Rockets were fired from time to time, the sixth launched after four hours on the bottom. By chance, a lookout on the Squalus' sister submarine USS Sculpin saw the rocket's smoke. Once the Sculpin made its way over the sunken Squalus, it found the phone buoy. However, soon after the two-way conversation began, the phone cable parted.
During the morning, conversation was limited to conserve oxygen. A review of the use of the Momsen Lung, an underwater breathing apparatus carried by subs at that time, was conducted in case the men had to leave the submarine through a lock and rise to the surface.
Most of the survivors were wet and became increasingly colder. The oxygen content of the air was decreasing, and in the early afternoon Lieutenant Naquin ordered the carbon dioxide-absorbing cakes to be opened. Oxygen under pressure in canisters was held in reserve. The slightly toxic air made the men drowsy, which promoted sleep. A second meal of beans, tomatoes and fruit was issued about 6:00 p.m.. Oxygen was bled into the stale air.
Two ships arrived on the scene during the afternoon. Their propellers could be heard clearly in the Squalus. One had an oscillator for generating underwater sound, making possible Morse code transmissions. The Squalus crew responded by laboriously beating out answers by hammering on the hull. One blow was a dot and two a dash. However, the sound from that depth was weak and was only heard occasionally was. By midnight, the water in the pump room below the 18 sailors in the control room had risen two feet. It was nighttime on the surface, and 243 feet might as well have been a million miles.
From the first news of the sinking, rescuers rushed to the scene. Charles "Swede" Momsen, the inventor of the Momsen Lung, two doctors and a diver left Washington, DC, from the Anacostia Naval Air Station by seaplane and landed at Portsmouth at 7:30 p.m. After transferring to a Coast Guard cutter, they arrived on station at 11:30 p.m. Admiral Cole got to Squalus' sister submarine Sculpin on a small vessel named Penacook, which then succeeded in hooking a grappling hook onto some part of the Squalus. The rescue vessel Falcon (ASR-2) a slow, former minesweeper also arrived on the scene. She was equipped with a rescue chamber, air pressure systems, and a recompression chamber for divers.
The rescuers learned that there were 33 survivors. There were three options to save the men. One was to pump out the flooded compartments to bring the Squalus to the surface. However, this was very risky, since the reason for the sinking was still not known. The second option was to have the men come to the surface using their Momsen Lungs. But their depth was somewhat greater than the 207 feet for which the Lung had been tested. The men were very cold and undoubtedly weak from the foul air and tension. Momsen recommended, and Admiral Cole concurred, that using the rescue bell to retrieve the men was the best choice. The rescue bell was a small craft tethered to a surface ship that could be lowered onto the sub's escape hatch. It would then equalize pressure between the two vessels and allow the sailors to be taken to the surface in small groups.
The morning of May 24 was overcast, with choppy seas, squalls and sometimes near-zero visibility. The Falcon, which was carrying the rescue chamber, dropped four anchors around the Squalus. After four hours of efforts, a fifth anchor was dropped by another ship and the line passed to Falcon. By 9:45 a.m., the rescue ship was held stationary, pointed into the wind and pitching heavily, but on station over the submarine. Fortunately, the seas became calmer and the air clearer.
Momsen and the divers moved to the Sculpin to learn the details of the submarine's structure, which was identical to Squalus. Back on Falcon, Momsen chose to use divers from both his crew and the Falcon in turns, for the morale of both groups. The first diver found that the grappling hook had caught the sunken submarine only about 10 feet from the hatch to which the rescue bell would attach. It took him 22 minutes on the submarine to simply attach a shackle with the line that would guide the chamber. The crew inside the Squalus responded to the sound of the divers footsteps by banging happily on the hull.
Momsen vetoed the idea of four trips, each bringing up seven men, and a fifth with the five remaining survivors. He worried that the fifth trip would greatly increase the risk of an accident. He decided a load of seven men first, then eight men and finally two trips of nine men. The bell, linked to the Falcon with a cable to haul it up, two air hoses and an electrical cable for lights and phone, descended with two operators for the motors, ballast, air pressure and communications. It measured only five feet in diameter, with a height of seven feet. The first trip delivered coffee and food and then brought up the planned seven men. With that historic partial rescue, it was learned in detail who had survived the sinking and who perished.
During the first ascent, the survivors in the control room donned their Momsen Lungs as gas masks and moved through the chlorine-contaminated forward battery room to join the other survivors in the forward torpedo room. The next descent took an hour, plus 45 minutes attached to Squalus taking on men and a half-hour ascent. It went smoothly, until the chamber surfaced riding low in the water. It seemed to Momsen that bringing up eight people was overloading the system, and he resigned himself to making a fifth trip. Then it was discovered that there were really nine survivors instead of the planned eight in the bell during the second trip, so Momsen could go back to his four-trip plan.
The third trip was routine. During the last ascent, the reel taking up the bell's cable became fouled. A diver was sent down to fix the problem, but was unable to do so. The buoyancy of the chamber had to be decreased to permit it to descend and settle on the bottom. First, one diver was sent down to attach a new cable. He failed, but he found that only one strand of the cable still attached to the Falcon remained. A second diver was also unable to put a new cable on the rescue chamber. Next, Momsen decided to try to adjust the buoyancy of the chamber so that it would rise slowly. Sailors on deck played the frayed cable in and out with the rise and fall of the ship on the waves. The chamber finally reached the surface, and the men were brought aboard the Falcon at 38 minutes after midnight on May 25. Thirty-nine terrible hours had elapsed since the sinking. The last group of survivors and the two operators were in the crowded chamber for over four-and-a-half hours. All of the men that had survived the sinking were safe on the surface, 33 of the original 59 crewmen.
In what turned out to be a monumental task, the Squalus was eventually raised and repaired. An investigation into the sinking found that a mechanical failure had occurred with the main induction valve, which brought in outside air to the sub's diesel engines when she was running on the surface. With the valve open when the ship dived, seawater had poured in a quickly flooded the after compartments. Some investigators, including Momsen, believed that one of the sailors had accidently opened the valve after the ship dived. However, no one in the after part of the ship lived through the sinking.
The Squalus was renamed the USS Sailfish and went on to survive twelve war patrols during the Second World War. Crews supposedly referred to the sub as the Squalfish. Several of the men who survived the Squalus sinking served on the Sailfish during the war. Lieutenant Naquin, the sub's first captain, was not one of them; he never served on a submarine again.