Encyclopaedia of Cryptozoology
Deepstar 4000 fish
Deepstar 400 fish Skin Diver

The Deepstar 4000 fish depicted as a giant ray-finned fish in Skin Diver.

Classification Osteichthyes
Proposed scientific names
Other names Deepstar monster
Sea reported Pacific Ocean
First reported 1967[1]
Prominent investigators Gardner Soule
Matt Bille

The Deepstar 4000 fish was a cryptid giant deep sea fish seen once, off southern California in the Pacific Ocean, by the crew of the Deepstar 4000↗ submersible during a 1966 dive.[2] It was estimated to have measured 25–40 ft (8–12 m) in length, equal to some of the largest known living fish, and far larger than any known bony fish.[3][4]



This fish was allegedly observed by pilot Joe Thompson (1930 – 2003) and possibly marine biologist Gene LaFond (1909 – 2002), during a June 1966 research dive in the San Diego Trough alongside instrumentation engineer Dale Good.[1] They had taken the Deepstar 4000 down to around 4,000 ft (1,219 m) to lay hydrographical instruments on the seafloor, and when Thompson happened to look through the window, he found himself staring into the eye of a giant fish which had swam briefly into view. It moved past quickly, bringing up silt from the seabed, before disappearing.[5][6] The sighting had only lasted for around 8 seconds.[1]

Thompson and LaFond kept quiet for more than half a year, assuming they would not be believed, but eventually described the fish to journalists Paul J. Tzimoulis[1] and Louis Schafer,[6] and cryptozoologist and marine writer Gardner Soule,[7] to whom Thompson also described a much smaller giant grenadier. Furthermore, according to Soule, the live reactions of the two men were recorded on the submersible's audio log.[7] Thompson asserted that LaFond had not been able to see the fish for himself,[1] but LaFond independently stated that he had seen it.[8]


Deepstar 4000 fish sketch

Line drawing of the Deepstar 4000 fish by Setofin and Truth is Scarier.

Thompson and LaFond were most impressed by the allegedly enormous size of the fish they reported, which somewhat resembled a sea bass in body form.[1][8] It was far larger than the 18 ft (5 m) Deepstar 4000, and was judged to be some 25–40 ft (8–12 m) in length, similar in size to some whale sharks (Rhincodon typus), but only 5–6 ft (1.5–1.8 m) across.[1] As well as the submersible itself, the pair were able to judge the fish's length using the hydrological instruments which had been recently placed on the seafloor at set intervals.[5] It possessed gill plates,[1] "huge pectoral fins"[6] 2 ft (60 cm) in length,[1] a rounded grouper-like tail fin which seemed to be 4–5 ft (1.2–1.5 m) in height[5] and "serrated":[6] Thompson was quite struck by this unusual tail, which he described in more detail as "very strange looking, with ragged caudals jutting off its end on a 30 degree angle ... not the tail of a sea bass or shark ... [i]t reminded me of an illustration of a coelacanth's tail."[1] Its eyes, one of which was the first thing Thompson saw, were "as big as dinner plates."[5] The skin was dark[5] and mottled "gray-black"[8] or "brown with grayish white tipping on the fin scales and tail,"[1] and Thompson was certain that it was also covered in scales,[6] with those towards the anterior portion of the body being the largest, around the size of coffee cups.[1]


Greenland shark

The Deepstar 4000 fish has sometimes been identified as a Pacific sleeper shark (Somniosus pacificus), a relative of the pictured Greenland shark (Somniosus microcephalus) (CC BY-SA 4.0).

Giant sleeper shark

Isaacs' "giant sleeper shark" photographs, from Baja California (left) and Hawaii (right), published in The Face of the Deep (1971) by Bruce Heezen.

Although the Deepstar 4000 was not able to photograph the giant fish, underwater cameras operated by oceanographer John D. Isaacs (1913 – 1980) in the same area soon produced a photograph of a large "marine monster". Ichthyologist Carl Hubbs (1894 – 1979) identified this as a Pacific sleeper shark (Somniosus pacificus), which were then confused with the better-known Greenland shark (Somniosus microcephalus), which is larger, but is restricted to the Arctic and North Atlantic. Isaacs, who was the Scripps Research Institute's resident "sea serpent expert,"[9] did not initally favour Hubbs' identification,[8] but several more photographs of sleeper sharks were later taken, and ultimately, given the number of times they appeared on camera, it was assumed that they must have been very common around the San Diego Trough.[4][10] It was Isaacs' "marine monster" photograph which initially induced Thompson and LaFond to come forward with their own sighting.[7]

Hubbs later suggested that the Deepstar 4000 fish could have been a very large specimen of this shark, although no sleeper shark is known to grow to the size estimated by Thompson.[2] Isaacs later reported photographing a 30 ft (9 m) sleeper shark near Hawaii,[8] but the average recorded size is some 12–14 ft (3–4 m) long. Other very large sleeper sharks have been reported, including a specimen filmed off Japan which has been falsely represented as a megalodon on the internet in the years after its recording. Richard Ellis also points out that sleeper sharks have comparatively small eyes, which would not warrant Thompson's "dinner plate" comparison.[3] Neither Thompson nor LaFond accepted the sleeper shark as what they had seen.[7] During the sighting, Thompson had briefly wondered if the fish was a giant sea bass, but he quickly and decisively decided that this was not the case.[1] Matt Bille feels that the animal was more likely an undescribed species, and observes that, if it was a bony fish rather than a shark, as appears to be the case, it would be by far the largest and heaviest on record.[2]

The largest known deep-sea bony fish is the Yokozuna slickhead, a member of the slickhead family (Alepocephalidae) which can potentially grow up to 9 feet long. Several details of the Deepstar 4000 fish, such as its large eyes, mottled grayish-black scales, pronounced gill plates, and rounded tail fin, closely recall those of a slickhead. It is possible that if it is indeed an undiscovered species, the mystery fish may be an enormous member of this group.

Notes and references[]

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Thompson, Joe & Tzimoulis, Paul J. "Monster of the Deep," Skin Diver, Vol. 16, No. 3 (March 1967)
  2. 2.0 2.1 2.2 Bille, Matthew A. (2006) Shadows of Existence: Discoveries and Speculations in Zoology, Hancock House, ISBN 9780888396129
  3. 3.0 3.1 Ellis, Richard (1998) Deep Atlantic: Life, Death, and Exploration in the Abyss
  4. 4.0 4.1 Soule, Gardner (1970) The Greatest Depths: Probing the Seas to 20,000 Feet and Below
  5. 5.0 5.1 5.2 5.3 5.4 Shenton, Edward Heriot "Where Have All the Submersibles Gone?," Oceans, Vol. 3, No. 6 (1970)
  6. 6.0 6.1 6.2 6.3 6.4 Schafer, Louis S. "The Deepstar 4000," The Compass: A Magazine of the Sea, Vol. 56, No. 1 (1986) – Online
  7. 7.0 7.1 7.2 7.3 Soule, Gardner (1968) Undersea Frontiers: Exploring by Deep-Diving Submarines
  8. 8.0 8.1 8.2 8.3 8.4 Behrman, Daniel (1969) The New World of the Oceans: Men and Oceanography
  9. Heuvelmans, Bernard (1968) In the Wake of the Sea-Serpents, Hart-Davis, ISBN 9780246643124
  10. Soule, Gardner (1981) Mystery Monsters of the Deep