Thread by @realscientists

Buckle in, everyone. I'm about to take you on a journey through the 20th century into modern times, and I'll be talking ocean exploration all the way. Let's get right to it, because the last century has been a whirlwind of tech and discoveries.

Yesterday, I left you with Alexander Agassiz’s coral reef studies in the Pacific, which took 6 years and investigated areas previously too remote for most Western explorers. Today, we begin with the year 1900 and the first modern submarine.

In 1900 A.D., the US Navy accepted its first submarine, the Holland. This sub was built by New Jersey native John P. Holland and had two motors - an electric one while submerged, and a gas engine on the surface.

(Photo: US Naval Institute)

The famous Scripps Institution of Oceanography became affiliated with the University of California (UC San Diego) in the year 1912, and hurtled up the ranks to become one of the world’s leading marine research centers today.

Also in 1912, German meteorologist and geophysicist Alfred Wegener proposes his theory of continental drift.

(Just so you know, this was a big deal. He was opposed rather vehemently. Though he was wrong on a lot, he got some stuff right and led to the theory of plate tectonics!)

1914 A.D. - The Canadian inventor Reginald Fessenden uses an oscillator for the first acoustic exploration of the sea floor, which eventually leads to the development of sonar.

(Photo c/o NOAA Photo Library)

1923 A.D. - The Coast and Geodetic Survey ship Guide is equipped with a Hayes sounding instrument. Over the next five years, nearly all of the Coast Survey ships are equipped with these or with similar deep-water acoustic sounding instruments.

1925 A.D. - Meteor, a German vessel, makes detailed measurements of the Atlantic Ocean using echosounding equipment, revealing new information about the ocean floor’s shape and structure.

(Photo: NOAA Photo Library, photolib.noaa.gov/htmls/ship3020…)

1925-1939 - The Coast and Geodetic Survey conduct systematic tracklines across many coastal areas around the US. These expeditions discover numerous seamounts, the Mendocino Escarpment, delineation of the basin and range topography of S. California, and many east coast canyons.

1930 A.D. - Another leading oceanographic research institution, Woods Hole, is founded in Cape Cod, Massachusetts.

1935 A.D. - Two men, William Beebe and Olis Barton, enter a tethered bathysphere and embark on the first deep ocean dive, reaching a depth of 3,000ft (914m) off the coast of Bermuda.

(Photo: Wildlife Conservation Society; NOAA)

1935 A.D. - The first offshore telemetering instrument, the automatic telemetering radio sonobuoy, is developed by Lt. Elliott B. Roberts of the Coast and Geodetic Survey, eliminating the need for manned station ships during RAR (Radio Acoustic Ranging) navigation operations.

1941-1945 A.D. - Military research from WWII leads to many new tools for ocean exploration: deep-ocean camera systems, early magnetometers, sidescan sonar instruments, and early technology for ROV guidance.

(Photo: Navigation lattice in W. Aleutians, 1945. NOAA Photo Library)

1943 A.D. - Jacque Cousteau and Emile Gagnan develop the first modern scuba system, the Aqua-Lung, which allows divers to stay underwater for longer periods of time and explore more effectively.

(Photo: Advertisement for the Aqualung from 1958)

1948 A.D. - The first untethered deep water craft, the bathyscaphe, has its inaugural dive with its inventor, Swiss physicist Auguste Piccard, as its passenger.

1951 A.D. - British vessel Challenger II probes the deepest point in the ocean, Challenger Deep, via modern methods: bouncing sound waves off the ocean floor 7mi below (Mariana Trench). It was previously sounded by the original HMS Challenger in 1875. (c/o Imperial War Museum)

1953 A.D. - Women were not permitted to work aboard research vessels until the 1960s, but geologist Marie Tharp still used sounding data from expeditions in the Atlantic Ocean to discover a rift valley.

(Photo: Lamont-Doherty Earth Observatory; estate of Marie Tharp)

Marie Tharp's discovered rift is later revealed to stretch over 40,000 nautical miles along the ocean floor and becomes known as the Mid-Atlantic Ridge. This discovery provides evidence for Wegener's theory of continental drift.

(Image c/o Library of Congress)

1954 A.D. - A French submersible, FNRS-3, sets the untethered submersible dive record off the coast of Senegal, West Africa. It reaches a depth of 13,290ft (4,050m).

1955 A.D. - The Coast and Geodetic Survey Ship, Pioneer, tows the first marine magnetometer in the Pacific and discovers magnetic striping on the sea floor, proving that the sea floor is spreading. This became known as the PIONEER Survey.

(Photo: NOAA Photo Library)

1955 A.D. - The US launches the USS Nautilus, the first nuclear-powered submarine. In its lifetime, it made over 2,500 dives and steamed over 513,500 nautical miles.

1960 A.D. - The deepest ocean dive, reaching a depth of 35,797ft (10,911m) is undertaken by the son of the bathyscaphe inventor, Jacques Piccard, using the Piccard-designed Trieste.

(Photo: Trieste prior to its historic dive. Thomas J. Abercrombie, National Geographic Society)

1961 A.D. - Scripps begins development of the Deep Tow sonar system, which becomes the forerunner of all remotely-operated and/or unmanned oceanographic systems today.

1962 A.D. - Harry Hess and Robert S. Dietz put it all together! They propose seafloor spreading as the mechanism that explains the presence of mid-ocean ridges. Particularly relevant, they note the importance of convection currents in the mantle for plate movement.

1963 A.D. - The first (operational) multibeam sounding system is installed on the USS Compass Island, allowing for a broader swath of seafloor to be mapped during a single survey line.

(Photo: From USS Compass Island Welcome Aboard handout)

1964 A.D. - The famous deep submergence vehicle, Alvin, is constructed by Woods Hole, becoming the first US deep diving sub and the first deep-sea -passenger- sub. During '64, Alvin explored the deepest point in the Caribbean Sea, the Cayman Trough. (Photo c/o WHOI)

1965 A.D. - The first underwater robot, Halibut, is developed by the US Navy.

(I just accidentally broke the thread, so I've deleted a few and have to start over from the Halibut tweet... my apologies, guys!)

1970 A.D. - The National Oceanic and Atmospheric Administration (NOAA) is established, becoming responsible for US weather/climate forecasting, ocean/atmospheric data monitoring and archiving, marine fisheries management, mapping of US waters, and coastal zone management.

1970 A.D. - Dr. Sylvia Earle leads the first all-female research expedition, Tektite II, during which teams of scientists live for weeks at a time in an enclosed habitat on the sea floor, 50ft below the surface.

(Photo: Earle during the 1970 project. C/o AP)

1977 A.D. - The first hydrothermal vents are discovered in the eastern Pacific using the submersible Alvin. This is revolutionary, as it is the first known ecosystem that thrives without using the energy of the sun and uses chemosynthesis instead (Photo c/o WHOI)

1979 A.D. - Dr. Sylvia Earle walks on the sea floor, unassisted, for 2.5 hours at a depth of 1,250 ft. She was wearing a pressured suit, but was attached only by a communication line to the accompanying submersible.

(Photo: Chuck Nicklin, National Geographic Creative)

1980 A.D. - Dr. Robert Ballard applies optical fiber technology for the first ‘telepresence', allowing video footage to be transmitted in real time from an underwater craft to a ship on the surface.

1982 A.D. - NOAA begins installing a buoy array in the equatorial Pacific following a major El Niño event. These have since helped predict future events and provided a further step up in understanding the relationship between ocean and atmosphere.

1985 A.D. - Dr. Ballard and his team discover the wreck of the Titanic using remotely-operated vehicle ‘Argo’, which was towed like a sled above the seafloor.

(Photo: history.com/topics/titanic…)

1986 A.D. - Dr. Ballard returns to the Titanic with the manned submersible, Alvin, and the unmanned ROV, Jason Junior (JJ).

(Photo: JJ peering into a Titanic stateroom, c/o WHOI)

1990 A.D. - The Argo program begins, deploying 3,000+ robotic probes throughout the global oceans to measure climate, weather, and sea surface height. The project took 17 years to deploy all of the probes.

1992 A.D. - Underwater laboratory, Aquarius, begins operation off the coast of Key Largo, FL, at a depth of ~50ft. Teams spend 10 days in the structure, venturing into the water for 6 to 9 hours a day for fieldwork. This revolutionized the study of coral reefs.

(Photo: WHOI)

1992 A.D. - The TOPEX/Poseidon satellite begins mapping the ocean’s surface from space.

(Graphic c/o NASA/JPL)

(Oh my goodness I can't keep a thread together, can I? SORRY GUYS 😅)

1995 A.D. - Geosat satellite radar altimetry data is declassified, leading to worldwide mapping of the sea floor from space by Walter Smith and Dave Sandwell. This effort significantly improved the accuracy of ocean basin maps.

(Map c/o UCSD, Walter Smith, Dave Sandwell)

2000 A.D. - Autosub, which is an autonomous submarine equipped with an array of scientific sensors, is launched by the Southampton Oceanography Centre. The sub is able to carry out pre-programmed missions and can reach regions of the ocean previously inaccessible.

(Photo: SOC)

2010 A.D. - The first global census of marine life is completed. It was a 10-year project between scientists from ~80 nations, and provided biodiversity data for global oceans. For more info, check out its website: coml.org

2011 A.D. - An expedition to the Mariana Trench discovers a single-celled amoeba (Xenophyophore) measuring 4 inches in diameter. Additionally, it is learned that trenches play a much larger role in regulating Earth’s chemistry and climate than previously thought.

(Photo: NOAA)

2012 A.D. - Director James Cameron is the first person to perform a solo dive to the bottom of the Mariana Trench, reaching a depth of 35,756ft (10,898m). He spends three hours on the bottom filming before returning to the surface.

(Photo: Mark Thiessen/National Geographic)

2012 A.D. - A Japanese expedition and film crew capture the first video of a live giant squid in its natural environment. Previous images and video have been only of dead squid.

(Photo: NHK/NEP/Discovery Channel)

2017 A.D. - Seabed 2030 is announced: an int'l effort that plans to map the entire floor of the Earth’s oceans by 2030 using 12+ ships outfitted with advanced multi beam bathymetry technology. As of today, < 20% of our oceans have been mapped in detail. seabed2030.gebco.net

OK! Well, as long as I haven't gone and broken everything again (I broke the thread twice. TWICE. I am ashamed. Should be fixed now) I'm off for the evening. Heading to job #2, during which twitter access is limited. Talk to you all soon! Send your questions and comments! 😘