What is the loudest sound ever made underwater?
Guinness World Records lists the Operation Wigwam nuclear test of 14 May 1955 as the loudest human-made underwater sound, with a shockwave calculated at 328 dB re 1 µPa at its point of origin. The US Navy detonated a 30-kiloton device 2,000 ft (610 m) deep off California.
- Level
- 328 dB re 1 µPadecibels relative to 1 micropascal, measured in water
- Daily limit
- Underwater levelnot an air level
What the numbers mean
How it was measured. Underwater level in dB re 1 µPa. Underwater decibels are not comparable with in-air decibels: see "underwater-vs-air". Guinness World Records: a shockwave calculated at 328 dB re 1 µPa at its point of origin for a 30-kiloton device detonated at 2,000 ft (610 m) depth off California on 14 May 1955. A calculated figure, not a measurement.
Operation Wigwam tested the effect of nuclear shock waves on submarine pressure hulls. Guinness World Records says the blast reverberated around the Pacific for several hours, and that a Navy hydrophone array at Kaneohe, Hawaii, picked up reflections from features as far away as French Polynesia: more than 6,200 km from the source, then another 4,400 km to Hawaii.
The 328 dB figure is a calculation for the point of origin, where the event is a shock wave rather than a sound in the ordinary sense. It is far above any sound made by an animal or machine in the sea; the loudest animal, the sperm whale, reaches 236 dB re 1 µPa at 1 m.
Is it dangerous?
Measured in water against a 1 µPa reference, so the number cannot be compared directly with levels in air. See the underwater note on the Scroll. Marine-mammal and diver exposure criteria use their own metrics and are outside the scope of this page.
Protecting your hearing
Not applicable. Underwater nuclear testing has not been carried out for decades.
Questions
What is the loudest human-made sound underwater?
Guinness World Records lists the 1955 Operation Wigwam nuclear test, calculated at 328 dB re 1 µPa at its point of origin.
How far did the Wigwam blast travel?
A hydrophone array in Hawaii detected reflections from French Polynesia, a path of more than 6,200 km plus 4,400 km.
Sources
- Loudest artificial sound underwater, Guinness World Records. Supports: 328 dB re 1 µPa (calculated).
The explosion generated a shockwave that was calculated to have been 328 dB (re 1 μPa) at its point of origin
Checked 2026-11-02.
This page is general information, not medical advice. If you have ringing in your ears, muffled hearing or any change in your hearing, see an audiologist or your doctor.