# The Bloop was a giant sea creature or secret military project

**Verdict: Contradicted.** NOAA's own hydrophone data traced the sound to an icequake (a large Antarctic iceberg cracking and calving), not a living creature or a classified weapon.

Category: Cryptids & Monsters · Era: Post–Cold War · First circulated: 1997 · Believed by: A durable internet legend, not a polled belief
URL: https://theconspiratory.com/theory/the-bloop

## Summary
In 1997, NOAA's Pacific hydrophones picked up one of the loudest sounds ever recorded in the ocean: a noise so powerful it briefly looked biological, and so mysterious it spawned a cottage industry of giant-squid and secret-submarine theories. The real source, confirmed years later from NOAA's own Antarctic recordings, was ice.

## The claim
That an ultra-low-frequency sound recorded by NOAA hydrophones in 1997, nicknamed 'the Bloop,' was made by an enormous unknown sea creature far larger than any known animal, or alternatively that it was evidence of a secret military test, and that NOAA's later 'icequake' explanation is a cover story.

## Origin and timeline
- 1997: NOAA's Equatorial Pacific autonomous hydrophone array (built on repurposed U.S. Navy SOSUS submarine-detection technology) records an extraordinarily loud, ultra-low-frequency sound. It is picked up on sensors more than 5,000 km apart.
- 2001: NOAA acoustician Christopher Fox and colleagues at the Pacific Marine Environmental Laboratory (PMEL) publish the sound's spectrogram and nickname it 'the Bloop.' Its profile rises rapidly in frequency and resembles a biological call, but at an intensity no known animal could produce.
- Mid-2000s: As the mystery spreads online, PMEL researchers move hydrophones progressively closer to Antarctica and begin recording large numbers of 'icequake' signals with spectrograms closely matching the Bloop's.
- Early 2008: While acoustically tracking the disintegration of iceberg A53a near South Georgia Island, PMEL records calving and fracturing events whose signatures line up with the original 1997 recording.
- 2012: NOAA formally describes the Bloop as consistent with a 'non-tectonic cryoseism' (an icequake from iceberg calving or seabed gouging by ice), closing the file on the mystery-animal explanation.

## The evidence, claim by claim
- Claim: The Bloop's audio profile resembled a biological call, and NOAA's own lead scientist said its sheer loudness pointed to something bigger than any known animal.
  Evidence: True, and it is the honest origin of the whole legend. Christopher Fox, the NOAA acoustician who worked the case, did note the rising-frequency shape looked animal-like, but he was describing an open scientific puzzle, not endorsing a monster. He also flagged ice calving as a candidate explanation as early as 2001, years before the theory escaped into pop culture.
- Claim: NOAA listed the Bloop as 'unidentified' for years, which is proof of a cover-up.
  Evidence: An unsolved case is not a hidden one. NOAA published the spectrogram itself, discussed the sound openly in public materials, and kept investigating using its own public hydrophone network, the opposite of suppressing the data. The 'unidentified' label reflected the state of the science, not secrecy.
- Claim: The sound was picked up on Navy-derived SOSUS hydrophone technology, so it must relate to a classified military program.
  Evidence: The array's lineage is real (NOAA's Equatorial Pacific hydrophones do repurpose former Navy submarine-detection infrastructure), but repurposed hardware is not evidence of a hidden payload. NOAA operates and publishes from that same network for tracking whales, earthquakes, and ice, and its icequake conclusion came from additional recordings made in the same transparent, civilian program.

## Why people believe it
- A real, unsolved scientific mystery (an unusually loud, animal-sounding noise from the deep ocean) is exactly the seed every good cryptid story needs, and this one came stamped with a government agency's own logo.
- The 1997 detection landed in the golden age of the early internet, where a strange NOAA spectrogram could travel fast, get nicknamed, and gather Lovecraft/Cthulhu jokes long before most readers ever saw the eventual explanation.
- It flatters a satisfying worldview: the ocean is vast and under-explored, official agencies are slow to admit what they don't understand, and the biggest, strangest sound ever recorded 'should' have a suitably enormous cause.

## Open questions
- NOAA's hydrophone data confidently place the 1997 sound's cause in the icequake family (a large iceberg cracking, fracturing, or scraping the seabed as it drifts) and the agency's own analysis of the sound's arrival angle narrows the likely source to somewhere between the Bransfield Strait and the Ross Sea, or possibly Cape Adare. But unlike the 2008 breakup of iceberg A53a, which helped confirm how closely icequakes can match the Bloop's spectrogram, no specific iceberg or calving event has ever been named as the actual source of the 1997 recording itself. That is a narrow, technical gap in an otherwise well-supported explanation, not a reason to doubt it: it points to how hard it is to trace one sound to one iceberg among many in the Southern Ocean, not to an animal or a classified program.

## Sources
- Acoustics Monitoring Program: Icequakes (Bloop), NOAA Pacific Marine Environmental Laboratory (PMEL) (2012): https://www.pmel.noaa.gov/acoustics/sounds/bloop.html
- What is the Bloop?, NOAA National Ocean Service (2023): https://oceanservice.noaa.gov/facts/bloop.html
- The Bloop: An Underwater Mystery That Took Nearly 20 Years to Solve, NOAA Pacific Marine Environmental Laboratory (PMEL) Acoustics Program: https://www.pmel.noaa.gov/acoustics/pmel-in-the-news/bloop-underwater-mystery-took-nearly-20-years-solve
- Spectrograms, PMEL Acoustics Program, NOAA Pacific Marine Environmental Laboratory (PMEL): https://www.pmel.noaa.gov/acoustics/specs_all.html
- Bloop, Wikipedia: https://en.wikipedia.org/wiki/Bloop
- Remember That Scary Undersea 'Bloop' Noise? At Last We Know What Caused It, Gizmodo (2012): https://gizmodo.com/remember-that-scary-undersea-bloop-noise-at-last-we-5962724
- The Sea Monster Goes 'Bloop'—Or Does It?, Popular Science: https://www.popsci.com/environment/sea-monster-bloop-sound/

Rated by The Conspiratory, a neutral, sourced encyclopedia of conspiracy theories. Full page: https://theconspiratory.com/theory/the-bloop