Humans have been exploring the seas from the earliest days of recorded history. Yet we still famously know more about the surface of the moon than we do about the oceans on this planet. Here are some of the most significant events in the history of our ongoing discovery of our watery world…

diving begins4500 BC

Ocean Diving Begins

Coastal cultures like those in Greece and China begin diving into the sea to gather food and engage in commerce. Diving is possibly even used in warfare.

1000 BC

Deep Diving Begins

The Greek poet Homer mentions sponge fishermen who dive as deep as 30 metres by holding onto a heavy rock. To compensate for the increasing pressure on their ears, they pour oil into their ear canals and take a mouthful of oil before diving. Once on the bottom, they spit out the oil, cut as many sponges free from the bottom as their breath will allow, and are pulled back to the surface by a tether.

500 BC

Treasure Diving Begins

King Xerxes of Persia commissions a diver named Scyllias and his daughter Cyana to dive for treasure during one of the many wars between the Persians and the Greeks.

414 BC

Diving Used in Warfare

The Greek historian Thucydides writes about diving used in warfare in his narration of the siege of Syracuse. His writings tell of Greek divers who submerge to discover and remove underwater obstacles from the harbour in order to ensure the safety of their ships.

360 BC

First Crude Diving Bell Design

The Greek philosopher Aristotle mentions the use of a sort of crude, air-supply diving bell. Aristotle wrote that “one can allow divers to breathe by lowering a bronze tank into the water. Naturally the container is not filled with water but air, which constantly assists the submerged man”.

325 BC

First Use of a Diving Bell

Alexander the Great made use of a crude diving bell to employ combat divers during the siege of Tyre. The diving bell contained coloured glass so that the divers could see through it. Alexander himself made several dives with the device to check on the progress of the work.

Alexander diving

325 BC

Voyage of Pytheas

The Greek astronomer and geographer Pytheas sails north from the Mediterranean and reaches the coast of England. He is the first person on record to describe the midnight sun north of the Arctic Circle. He also developed methods for using the sun and the North Star to determine latitude.

200 BC

Circumference of the Earth Discovered

The Greek astronomer Eratosthenes becomes the first person to discover the circumference of the Earth. He uses the angles of shadows and the distance between Alexandria and Syene to arrive at a value of 40,000 km. The actual circumference of the Earth is 40,032 km.

150 BC

Ptolemy’s Map

The Greek astronomer and geographer Ptolemy produces a map of the ancient world that includes the continents of Europe, Asia, and Africa as well as the surrounding oceans. This early map is one of the first known to include lines of latitude and longitude.

Ptolemy map

200 – 100 BC

Chinese envoys sailed into the Indian Ocean and reportedly reached Kanchipuram, known as Huangzhi, or Ethiopia.

200 AD

First Indicated Use of Goggles

Artwork on Peruvian pottery shows divers wearing goggles and holding fish.

300 AD

Polynesian Exploration and Colonisation begins

The Polynesians begin to explore and populate the great Polynesian triangle, from Easter Island, to Hawaii and New Zealand. They were among the first known people to explore the mysteries of the ocean and marine life. Their expeditions continue until 1275 AD.

priests across kaelakekua

900 AD

Viking Expeditions Begin

The Vikings begin to explore and colonise Iceland, Greenland, and Newfoundland. They are among the first to use the North Star to determine their latitude.

1002 AD

Voyage of Leif Erikson

Norse explorer Leif Erikson becomes the first European to land in North America, nearly 500 years before Christopher Columbus. He calls the new land Vinland and establishes a Norse settlement in what is now the northern tip of Newfoundland in Canada.

1031 – 1096 AD

Discovery of True North

Chinese scientist Shen Kuo describes the magnetic needle compass, which uncovers the concept of true north and enables more accurate navigation. The idea of the magnetic compass would not make its way to Europe until 1190 AD, but it would be another three centuries before European navigators would fully understand and use it
for navigation.

Shen Kua


First Recorded Circumnavigation of the World

Ferdinand Magellan and his fleet depart Portugal to begin a daring voyage of discovery. The fleet would become the first to sail around the world. Magellan does not live to see their accomplishment. He dies on the Island of Mactan in the Philippines in 1521 from the poison arrows of the local natives.


Chinese Exploration of the World

Under Admiral Zheng He, a Chinese fleet of more than 300 massive ships (the biggest fleet ever launched) rounds the Cape of Good Hope, travels up the coast of Africa, and probably crosses the Atlantic Ocean. Aboriginal legends also make it likely that these Chinese explorers reached Australia. Around the same time, another Chinese explorer, Zhou Man, is also thought to have explored the western coasts of North and South America.


First Voyage of Endeavour

Lieutenant James Cook embarks on a voyage to observe a transit of the planet Venus across the sun. During this and two voyages to follow, Cook would explore and map the Pacific Ocean. He is the first person to use a chronometer to accurately determine longitude at sea.

Hodges resolution


Franklin’S Sundry Maritime Observations

American inventor Benjamin Franklin writes a lengthy letter to a scientific colleague in France. Known as his Sundry Maritime Observations, the letter announces the discovery of the Gulf Stream and touches on a wide range of maritime subjects such as ship propulsion methods, hull design, and causes of disasters at sea


Voyage of the H.M.S. Beagle

English naturalist Charles Darwin departs England aboard the H.M.S. Beagle. The goal of the expedition is to perform a survey of Patagonia and Tierra del Fuego. Darwin studies the plants and animals at each new stop. He discovers many unique species on the Galápagos Islands off the coast of Peru in South America. These discoveries lead to his groundbreaking theory of evolution. In his book, On the Origin of Species, Darwin suggests that the deep ocean may be a sanctuary for living fossils.


Discovery of Deep Sea Life

Edward Forbes’ theory on deep sea life is called into question when Louis F. de Pourtales of the U.S. Coast Survey examines Coast Survey sounding operations that find indications of life in depths over 1000 fathoms (1,830 metres).


First Deep Sea Canyon Discovered

James Alden, commanding officer of the Coast Survey Steamer Active, discovers the first known deep-sea canyon, now known as Monterey Canyon. This canyon extends 153 metres into the Pacific Ocean and reaches a depth of 3.5 kilometres.

submerged valley 1857


Proof of Deep Sea Life

Naturalist Louis F. de Pourtales conducts dredging operations off the southern coast of Florida. He finds prolific life extending below 300 fathoms (550 metres).


Deep Sea Life in Abundance

Scottish naturalist Charles Wyville Thomson dredges the ocean floor and discovers life as deep as 2,400 fathoms (4,389 metres). This evidence finally disproves Edward Forbes’ theory of a lifeless (azoic) zone below 300 fathoms (550 metres).


Early Marine Survey of the Americas

Swiss naturalist Louis Agassiz takes the steamship Hassler on a biological survey of the Americas, collecting and cataloguing more than
30,000 specimens of marine life.


Voyage of the H.M.S. Challenger

The H.M.S. Challenger sails from Portsmouth, England and begins a four-year journey around the world. During the voyage, scientists test the salinity, temperature and density of the seawater. Information is also collected about ocean currents, sediment, and meteorology. The crew discovers underwater mountain chains and hundreds of species previously unknown. This research is eventually consolidated into a fifty-volume research report known as The Challenger Report. This research forms the basis of modern oceanography.

challenger hms


Marine Survey of the Pacific

Swiss zoologist Alexander Agassiz makes several expeditions on the steamship Albatross to study coral reefs in the Pacific Ocean. The ship’s crew makes soundings and collects specimens from islands and atolls in the South Pacific. Over the next six years, the expeditions discover an abundant range of marine life from previously unexplored remote regions.


First Deep Ocean Dive

William Beebe and Otis Barton embark on a deep sea expedition in a tethered sphere known as a bathysphere. They reach a depth of  914 metres off the coast of Bermuda and discover a previously unseen world of bizarre, luminescent creatures.

beebe barton


Mapping the Ocean Floor

The German vessel Meteor sails around the Atlantic Ocean taking detailed measurements of the ocean floor using echo-sounding equipment. These voyages reveal new information about the shape and structure of the ocean floor.


Deepest Ocean Point Found

The British ship Challenger II bounces sound waves off the ocean bottom and locates what appears to be the sea’s deepest point. It is subsequently named the Challenger Deep. The site is found in the Mariana Trench. If you could put Mount Everest on the ocean floor in the Mariana Trench, its summit would lie about a mile below the ocean surface.


Discovery of Mid-Atlantic Ridge

American geologist Marie Tharp studies sounding profiles from the Atlantic Ocean and discovers a rift valley. Later studies reveal it to be a continuous rift valley extending over 40,000 nautical miles along the ocean floor. This discovery provides evidence for the newly formed theory of continental drift, known today as plate tectonics.


Magnetic Striping Discovered

In a joint project with the U.S. Navy and the Scripps Institution of Oceanography, the Coast and Geodetic Survey Ship Pioneer tows the first marine magnetometer and discovers magnetic striping on the sea floor. This discovery proves that the sea floor is spreading, providing significant credibility to the theory of plate tectonics.


Deepest Ocean Dive

Jacques Piccard and two other men descend into the ocean to a depth of 10.9 kilometres. They make the trip in the Trieste, a sturdy underwater vehicle known as a bathyscaphe. The divers discover amazing deep-sea life at these tremendous depths.

fauna hydrothermal


Hydrothermal Vents Discovered

Scientists aboard the submersible, Alvin, discover and document incredible deep sea hydrothermal vents in the eastern Pacific Ocean. Hot water pouring from these vents enriches the water with nutrients and provides food for bacteria and a host of other organisms. This discovery rocks the scientific community because, for the first time, an ecosystem has been found that thrives without the energy of the sun; instead, these ecosystems thrive on chemical energy through a process known as chemosynthesis.


Atocha Found

Famed treasure hunter Mel Fisher finds the wreck of the Atocha which yields the biggest treasure ever recovered from a shipwreck.


Titanic Found

Dr. Robert Ballard, with the help of a tiny robotic submarine named Jason, discovers the wreck of the Titanic.



Seafloor Mapping from Space

Declassification of GEOSAT satellite radar altimetry data leads to worldwide mapping of the sea floor from space.


Disappearance of 90% of Large Fish

Scientific research leads to the discovery that we have lost 90 percent of all the ocean’s predatory fish. Despite this alarming evidence, fisheries continue with “business as usual”


Underground Ocean Discovered

A vast “ocean” of water is found trapped within rocks, 700 to 1,400 kilometres under the surface of the Asian continent. While the water makes up less than 0.1-precent of the rocks’ composition, the reservoir is roughly the size of the Atlantic Ocean.


Census of Marine Life Completed

The first ever global census of marine life is completed. This 10-year project involves 2,700 scientists from 80 nations. The census reveals what, where, and how many lives and hides in global oceans and is made available in an online directory that allows anyone to map global addresses of species.


Mariana Trench Expedition

An expedition crew returns to the Mariana Trench using modern submersibles. Among the new discoveries is a single-celled amoeba that measures an incredible 10 centimetres in diameter. Scientists also learn that trenches play a larger role in regulating the Earth’s chemistry and climate than was previously thought.


Discovery of the True Rate of Ocean Warming

More accurate data gathered by NOAA reveals that we had been underestimating the temperature of our oceans, and Earth’s surface temperature in general. Scientists discover that the actual warming of the previous 15 years was actually twice as much as had been estimated.


Lost Continent Discovered

A huge fragment of the prehistoric “supercontinent” is found off the coast of Mauritius. The discovery has led to speculation that there may be more pieces of this ancient landmass scattered through the Indian Ocean. Scientists are naming the continent “Mauritia”.

With special thanks to for permission to republish much of their comprehensive Ocean Exploration timeline.

The timeline was taken from our magazine – Asian Diver, Issue 2/2017. Click on the image to purchase your copy. 

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