Are these sounds all “solved” now?

Many are: Bio-Duck/Boing/“Star Wars” are minke whales; Bloop/Julia/Slow Down/The Train often trace to ice. Upsweep remains debated.

Where do the recordings come from?

Primarily NOAA/PMEL hydrophone arrays, WHOI collaborations, and academic expeditions across the Pacific and Antarctic.

Is the 52-Hz Whale a new species?

No confirmed species—likely an individual with atypical call frequency or a hybrid.

Could any sound be man-made?

Plenty of ocean noise is anthropogenic, but these classic entries show natural acoustic signatures unless noted otherwise.

10 Creepy Sounds from the Deep Ocean: Bloop, 52-Hz Whale, Upsweep & More

Updated on: September 30, 2025

Compilation image for deep ocean mystery sounds: spectrograms and dark sea — Scary and mysterious sounds from the deep ocean.

The ocean is still mostly unknown—and sometimes it screams. Hydrophones keep catching eerie noises: whales that sing at the wrong pitch, quacking seas, sirens that rise for minutes, and rumbles that echo like passing trains. Here’s a curated list of the strangest deep-sea sounds ever recorded, with quick explanations and source links.

TL;DR

Many “mystery” ocean sounds have natural sources: iceberg quakes, volcanoes, and minke whales.
Some are still debated (e.g., Upsweep), but NOAA/WHOI hydrophones provide best-in-class recordings.
Yes, the 52-Hz Whale is real—its call is just at an unusual pitch.

🧭 Jump to: 52-Hz Whale · Bio-Duck · Boing · Bloop · Julia · Slow Down · Star Wars · The Train · Upsweep · The Whistle · FAQ

10 Unexplained (and Explained) Noises from the Deep

1) 52-Hz Whale — “The Loneliest Whale”

A whale-like call centered near 52 Hz, atypical for blue/fin whales. Tracked for years across the North Pacific; identity remains uncertain, but it’s likely an individual with unusual vocal characteristics—not a new species.

Listen to the abyssal 52 Herz whale sound:

More: 12 years of tracking · WHOI feature

2) Bio-Duck — Quacking Seas

First logged by subs in the 1960s, this “quack” baffled researchers until acoustic tags on Antarctic minke whales solved it.

Listen to the baffling Bio-Duck sound:

More: Royal Society Biology Letters

3) The Boing — Hawaii’s Odd Ping

A distinctive “boing” logged since the 1950s off California and Hawaiʻi. Source identified as North Pacific minke whales by NOAA SWFSC acousticians.

Learn more about the strange Boing sound:

More: NOAA SWFSC · JASA paper (PDF)

4) The Bloop — Legend of the Deep

1997 low-frequency blast, detected thousands of km apart. Initially hyped as a sea monster; later studies point to icequakes / iceberg fracturing near Antarctica.

Listen to the eerie Bloop sound:

More: NOAA PMEL

5) Julia — A Long Whine (1999)

Recorded March 1, 1999; likely iceberg grounding between the Bransfield Strait and Cape Adare.

Listen to the mysterious Julia sound:

More: NOAA PMEL

6) Slow Down — The Falling Siren (1997)

A descending howl (May 19, 1997). Best hypothesis: iceberg keel dragging and slowing along seafloor.

Listen to the chilling Slow Down sound:

More: NOAA PMEL note

7) “Star Wars” — Laser Blaster Seas

A comical laser-like “ba-ba-boing” once blamed on ships; now attributed to dwarf minke whales in Australia.

Listen to the unexpected Star Wars sound:

More: NatGeo report

8) The Train — Horns on the Seafloor

Recorded March 4, 1997 in the Ross Sea. Sounds like a distant train rolling past—again, likely an iceberg keel grinding along the bottom.

Listen to the rumbling train sound:

9) Upsweep — The Seasonal Siren

First heard in 1991: narrowband upsweeping tones that peak in spring/fall. Origin is unsettled; hypotheses include hydrothermal/volcanic activity interacting with seawater.

Listen to the unexplained Upsweep sound:

More: NOAA PMEL page

10) The Whistle — Volcanic Whirr?

Captured July 7, 1997 in the eastern Pacific. A single undulating tone; researchers compare it to signals during submarine volcanic eruptions.

Listen to the puzzling Whistle sound:

More: NOAA PMEL

❓ Deep-Ocean Mystery Sounds — FAQ

Are these sounds all “solved” now?: Many are: Bio-Duck/Boing/“Star Wars” are minke whales; Bloop/Julia/Slow Down/The Train often trace to ice. Upsweep remains debated.
Where do the recordings come from?: NOAA/PMEL and partner arrays (hydrophones) across the Pacific/Antarctic; plus WHOI and academic expeditions.
Is the 52-Hz Whale a new species?: No confirmed species. It could be a blue/fin hybrid, an anomalous individual, or a normal whale with unusual call frequency.
Could any sound be man-made?: Some ocean noise is anthropogenic (ships, sonar), but the famous entries here have natural acoustic signatures unless noted otherwise.

Know another weird ocean sound? Drop it in the comments. And yes, we’ll keep chasing the ones we can’t explain—yet.

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