7 Unsolved Mysteries About the Deep Ocean | Summary and Q&A

April 3, 2016
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7 Unsolved Mysteries About the Deep Ocean


The ocean, covering over 70% of the Earth's surface, remains largely unexplored with many unanswered questions about its floor, underwater life, brine pools, milky seas, unique whale songs, unexplained ocean sounds, and the phenomenon of deep-sea gigantism.

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Key Insights

  • 🤣 The ocean floor remains largely unexplored, with only 5% seen by humans, highlighting the need for better mapping techniques.
  • 🛟 Life exists beneath the seafloor, challenging our understanding of the deep-sea environment and potentially providing insights into the history of terrestrial life.
  • 👻 Brine pools are unique saltwater lakes under the ocean's surface, hosting microorganisms adapted to extreme conditions.
  • 🌊 Milky seas, characterized by glowing ocean surfaces, are still not well understood, with bioluminescent bacteria and algal blooms implicated.
  • 🐳 The 52 hertz whale, with its unique song, raises questions about whale communication and possible hybridization.
  • 👂 Unexplained ocean sounds like Upsweep indicate ongoing mysteries in understanding underwater acoustics.
  • 🤢 Deep-sea gigantism remains a fascinating phenomenon with multiple theories but lacks a definitive explanation.


Humans have done a pretty good job of exploring the Earth thus far, climbing mountains and crossing continents and planting our flags all over the place in the name of science. But one part of the world that has remained pretty mysterious to us also happens to cover more than 70% of its surface: the ocean. Yes , we’ve sailed across it plenty of tim... Read More

Questions & Answers

Q: Why do we know less about the ocean floor than the surfaces of other planets?

The ocean floor remains largely unexplored because only 5% has been seen by humans, while advanced mapping of other planets has been done with higher resolution. Accessing the deep-sea environment is challenging and requires advanced technology.

Q: How do brine pools differ from the surrounding ocean, and why do some have mussels while others don't?

Brine pools have a higher salt content due to the mixing of seawater with buried salt deposits. The specific variations between brine pools and the presence of mussels are still not fully understood, as their differences and ecological factors are yet to be determined.

Q: What causes the phenomenon of milky seas, and why are they not well understood?

The exact cause of milky seas is still not clear, but the prevailing theory suggests massive colonies of bioluminescent bacteria growing on top of algal blooms. However, the formation, glow, and disappearance of these bacteria masses remain unidentified.

Q: Why does the 52 hertz whale produce a unique high-pitched song, and are other whales able to hear it?

The reasons behind the 52 hertz whale's distinct song are unknown, but it is speculated that it may be a result of malformation or hybridization. While other whales might be able to hear the song, whether they understand it remains uncertain.

Q: What are some possible explanations for the mysterious sounds like Upsweep recorded in the ocean?

Upsweep is a repeating "boop" sound heard regularly in the Pacific Ocean. It is associated with volcanic and seismic activity but has an unresolved origin according to NOAA. Researchers continue to explore possible causes and connections to underwater phenomena.

Q: What are some theories about the factors that contribute to deep-sea gigantism?

Theories like Bergmann's Rule, Klieber's Law, and resistance to increased pressure in the deep sea have been proposed to explain deep-sea gigantism. However, conclusive biological reasons are still lacking, and ongoing research aims to uncover the underlying mechanisms.

Summary & Key Takeaways

  • The ocean floor is mostly unexplored, with only 5% seen by humans, and we have a better understanding of other planets than the seafloor.

  • Life exists beneath the seafloor, with microbes found kilometers below the ocean's surface, possibly related to terrestrial organisms from millions of years ago.

  • Brine pools, saltwater lakes under the ocean, have unique compositions and are home to high concentrations of halophilic microorganisms.

  • Milky seas, areas of the ocean that glow brilliantly, are caused by unidentified bioluminescent bacteria.

  • The 52 hertz whale, producing a unique song at a higher pitch than most whales, raises questions about whale communication and possible hybridization with other species.

  • Unexplained ocean sounds like Upsweep continue to puzzle researchers, with its origin still unresolved.

  • Deep-sea gigantism, where many deep-sea creatures grow to unusually large sizes, remains a mystery with temperature, metabolic rates, and pressure theory as potential explanations.

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