Several Wikipedia articles, (Bathyscaphe, Trieste and Challenger Deep), about the 1960 Bathyscaphe Trieste trip to Challenger Deep, the deepest part of the Mariana trench, mention observations of lifeforms on the deep sea floor:

  • "The bathyscaphe was equipped with a powerful light, which illuminated a small flounder-like fish,"
  • "some type of flatfish, resembling a sole, about 1 foot long and 6 inches across"
  • "While on the bottom, Piccard and Walsh observed a number of small sole and flounder swimming away," (uncited)

These observations have been challenged because these types of fish are not believed to be able to survive at the cited depth. The video footage from the more recent Kaikō ROV and the autonomous Nereus HROV did not see any fish.

However, to date humans have only been able to survey a tiny percentage of the trench, which means it might be premature to preclude the existence of fish at that depth. To date, the world's deepest video footage of a fish was filmed at a depth of 7,703 meters.

Non-scientific reference:

  • This YouTube video, titled "Megalodon sighted in Mariana Trench", does not link to any scientific publication, nor does it state the depth at which the video was taken.

A second quote reinforces the accusation that the crew could not have plausibly seen the marine lifeforms (emphasis added):

... Their early departure from the ocean floor was due to their concern over a crack in the window caused by the intense pressure of their descent, and also because their landing on the sea bed had stirred up a cloud of silt which reduced visibility to zero and showed no sign of settling.

For reference, there is a video from Nereus HROV showing what stirring and settling could mean at the floor of the Challenger Deep.

Finally, the depth of the Challenger Deep had been measured to the same ballpark figure nearly a decade ago: (with the understanding of depth variations within the trench)

In 1951, ... the entire Mariana Trench was surveyed by a second Royal Navy vessel, ... also named HMS Challenger, after the original expedition ship. ... A depth of 10,900 m was measured.

My question is: Were those fish claims misattributed, or misquoted? (Wikipedia included.) If so, can we trace it to the original words from the Trieste crew and the source of the mistake?


  • Misquote: the juxtaposition of several phrases that are taken out of context.
    For example, (i) a flatfish seen during the descent and (ii) an observation of the cloud of silt at the sea floor could be taken out of context to mean (iii) a flatfish seen at the sea floor and (iv) a cloud of silt seen during the descent.
  • Misattribution: the phrases were quoted from a person not part of the Trieste crew, and thus cannot be taken as eyewitness testimony.

To assist in the search for the original source, here is the citation. The reference URL on the Wikipedia article has been broken. (Copied from a Google search result - restrictions may apply.)

  • Ref Type: Journal Article
  • Authors: Heppenheimer, TA
  • Year: 1992
  • Title: To the bottom of the sea
  • Journal: American Heritage of Invention & Technology
  • Volume: 8
  • Issue: 1
  • Pages: 28-38
  • ISSN: 8756-7296
  • @jwenting: my question could be taken at an objective scientific angle: Did the Challenger expedition make any physical measurements using equipments that were lowered into the 10000m+ depth (such as water samples, conductivity, temperature, salinity, speed of sound, opacity etc.) that were one-of-its-kind that would later verify that the equipment had actually visited that depth? I have seen pictures of the bathyscaphe and I have no problem accepting that the sphere, if lowered into that depth, would survive. But the encyclopedia quotes on fish are what I am questioning.
    – user2547
    Sep 6, 2011 at 7:08
  • 1
    @jwenting: I admit, with apology, that the current title (and the weak/strong questions) were tweaked for attention-grabbing. It was a somewhat unfortunate nature of the Skeptics.SE site. The focus of my skepticism is on the claims of "fish on sea floor at 10000-plus meters", and its derived claims. Nothing else.
    – user2547
    Sep 6, 2011 at 7:13
  • 2
    in other words, you claim that they were telling lies when they said they'd photographed those creatures at those debts, without backing up those claims. That's the core of a conspiracy theory, and impossible to refute as you could (as conspiracy theorists always do) claim that anything we can show you must also be based on lies. It's not as if we can as SE build a sub to take you down there to see for yourself, which experience you might well also challenge as being faked...
    – jwenting
    Sep 6, 2011 at 8:04
  • 1
    "A second quote reinforces the accusation that the crew could not have plausibly seen the marine lifeforms (emphasis added): ... Their early departure from the ocean floor was due to their concern over a crack in the window caused by the intense pressure of their descent, and also because their landing on the sea bed had stirred up a cloud of silt which reduced visibility to zero and showed no sign of settling." They actually saw the fish (or whatever it was) right BEFORE landing and stirring up the bottom. And the window was not their viewing window, by the way. I believe it was some sort of
    – user6543
    Mar 27, 2012 at 21:07

2 Answers 2


Jacques Piccard wrote that they saw a fish in the Challenger Deep on board Trieste,

"Fish Meets Sphere on Bottom ...And to demonstrate well all the significance of this dive, nature would have it that the Trieste come down on the bottom a few feet from a fish, a true fish, joined in its unknown world by this monster of steel and gasoline and a powerful beam of light. Our fish was the instantaneous reply (after years of work!) to a question that thousands of oceanographers had been asking themselves for decades.

Slowly, very slowly, this fish—apparently of the sole family, about a foot long and half as wide—moved away from us, swimming half in the bottom ooze, and disappeared into the black night, the eternal night which was its domain."

This article was originally published in the August 1960 issue of National Geographic magazine and retains the original language and spellings.

Man’s Deepest Dive

By Jacques Piccard

this entire article is now at: http://deepseachallenge.com/the-expedition/1960-dive/

  • 1
    is it possible they carried it down with them?
    – endolith
    Nov 4, 2012 at 1:44
  • 1
    @endolith The question is "Did people see fish in the trench" not if they reside there. But anyway, if it's able to survive the pressures, why can't it live there? This is assuming it wasn't injured by the pressure, maybe that is why it was moving slowly. Jul 24, 2015 at 17:27

One of the articles on Discovery says

On January 23, 1960, explorers Jacques Piccard and Don Walsh dove via their sub, the Trieste, into the Pacific Ocean's Marianas Trench, a 1,600-mile-long, arc-shaped, undersea chasm east of the Philippines. With more than a mile to go, the outer layer of a porthole cracked under the pressure of six miles of sea water. As they told the UK's Daily Mail, "It was a pretty hairy experience." Nonetheless, they reached 35,810 feet below sea level. To date, no one has broken the record.

This at least clarifies the main topic of the question - humans did reach at least 10k+ metres below sea-level.

Other references of exploration:

Only two other vehicles have succeeded in reaching the Mariana Trench: the U.S. Navy-built bathyscaphe Trieste, which carried Jacques Piccard and Don Walsh there in 1960, and the Japanese-built robot Kaiko, which made three unmanned expeditions to the trench between 1995 and 1998.

The challenger deep is located near the southwestern extremity of the Mariana Trench and was first explored in 1960 by Swiss scientist Jacques Piccard & US Navy Lt. Donald Walsh in bathyscaph "Trieste", a US Navy owned submersible manned vessel (Designed by Jacques Piccard's father Auguste) which set a record by diving to a depth of 10, 900 meters (35,810 feet).

  • 2
    And what about the fish?
    – M.K.
    Sep 11, 2011 at 22:58
  • 3
    The question has changed since the last time I answered. When I answered it, it was something like - Did humans explored Mariana Trench to its depth?
    – Harsh
    Sep 12, 2011 at 11:58
  • 6
    Moving targets are more difficult to hit.
    – user3344
    Feb 21, 2012 at 15:43
  • I apologize for changing the question. In its original form it would have been voted for deletion.
    – user2547
    Mar 27, 2012 at 3:14

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