USS Muskallunge (SS-262) was an American-built Gato-class submarine that served in the U.S. Navy between 1943 and 1957 before it was transferred to the Brazilian Navy, where it was renamed Humaitá (S14) and served between 1957 and 1968. Muskallunge was built at the Electric Boat Company in Groton, Connecticut. Construction began on April 7, 1942, and it was commissioned on March 15, 1943. 

Muskallunge had an overall length of 95.02 meters, a beam of 8.31 meters, a draft of 5.18 meters, a test depth of 90 meters, and a displacement of 1,525 tons surfaced and 2,424 tons submerged. It was equipped with 10 21-inch torpedo tubes, 6 forward and 4 aft, and could carry 24 torpedoes. It also had one 3-inch deck gun and a Bofors 40-millimeter cannon.

During World War II, Muskallunge took part in seven war patrols in the Pacific Theatre, between September 1943 and January 1944, April 1944 and December 1944, and April 1945 and August 1945. After the war, the U.S. Navy retained Muskallunge in its Atlantic Reserve Fleet from 1947 to 1957. In January 1957, the United States loaned the submarine to the Brazilian military as part of the Military Assistance Program. Reclassified as Humaitá, it served with Brazilian forces until its return to the United States in March 1968. On July 9, 1968, Muskallunge was used as a live-fire target for USS Tench and sank off Long Island, New York.

Muskallunge was rediscovered and explored on June 26, 2021, during a NOAA Ocean Exploration shakedown expedition aboard NOAA Ship Okeanos Explorer. Remotely operated vehicle (ROV) Deep Discoverer — equipped with an Insight Pacific Zeus Plus camera capable of collecting high-definition footage — was used to document the site, which is at a depth of approximately 635 meters and broken into two large sections: the bow section, which is approximately 60 meters long, and the stern section, which is approximately 30 meters long.

The footage used for the three photogrammetric models of the site was from timestamps 14:45 to 16:35 for the bow section and 17:45 to 19:00 for the stern section. This footage was processed into still images using Photoshop and was not color corrected. 9,169 images were used for the three photo models of the site (the bow sectin Nameon, the port side of the stern section, and the starboard side of the stern section). The footage collected during exploration of Muskallunge was not intended for photogrammetry. While aligning the models, there was some distortion at the break point on the stern section that caused the starboard side to align perpendicular to the port side. To address this, individual models were made for the starboard and port sides of the stern section.

The full annotated video of this dive can be viewed on SeaTube.

Site Name: USS Muskallunge (SS-262)

Type: UCH

UCH Vessel Date Built: December 13, 1942

UCH Vessel Date Sank: July 9, 1968

Hull Material: Steel

Official Number: SS-262/S14

Expedition Number: EX2103

Expedition: 2021 ROV Shakedown

ROV Dive Number: 11

ROV Dive Date: June 26, 2021

Location: Mid-Atlantic Canyons

Depth: 635 meters

Length: Bow section approximately 60 meters; stern section approximately 30 meters

Width: 8.31 meters

ROV Used: Deep Discoverer

Camera Information: Insight Zeus Plus HD, 3-CCD color camera with 2/3-inch 2,200,000 pixel 1080i IT CCDs

Video or Stills: Video

Number of Images Used/Format: 9,169/JPG

Image Alignment Percentage: 99%

Number of Tie Points: 1,695,729

Link to Raw Video Footage:,Stream,Highlight&camtype=CP,ROV,SHIP&oerkey=DIVE11&westbc=-180&northbc=90&southbc=-90&eastbc=180

Time to Complete: 8 hours

Orthomosaic Views Available: No

Images Available: Yes

Animations Available: Yes

Available File Exports/Location/POC:

Link to NOAA Ocean Exploration Project Page:

Software: Agisoft Metashape Standard Version 2.0.1.

Developer: Raymond Phipps, NOAA Ocean Exploration explorer-in-training, July 4, 2023.

Credit: Model courtesy of NOAA Ocean Exploration, 2021 ROV Shakedown.