View of Nature in Descending Regions circa 1893

Nature in Descending Regions was first published circa 1893. This chart offers a cross-sectional view of marine life and underwater habitats. Labels for the three main oceans are illustrated on the chart below the sea bed: the Atlantic, Pacific, and Indian, with the continents of North America, South America, Africa, Europe, and Asia labelled at the top of the illustration. References to the known marine life found in each feature a wide variety of marine life, including sharks, blowfish, whales, porpoises, cuttlefish, octopus (called Devil Fish), lobsters, hermit crabs, jellyfish, starfish, sea anemones, underwater plants, and corals. Sea urchins were of particular interest to scientists at the time this illustration was first published due to the infamous research being conducted by German biologist Theodor Boveri at Stazione Zoologica in Naples. The fossil record dates from the Ordovician period, some 450 million years ago. Ordovician rocks have the distinction of occurring at the highest elevation on Earth, at the top of Mount Everest. During this period, the area north of the tropics was almost entirely ocean, and most of the world's land was collected into the southern supercontinent Godwana, incorporating present-day South America, Africa, Arabia, Madagascar, India, Australia, and Antarctica. The name 'Godwanaland' was originally coined by Austrian geologist Eduard Suess (b. 1831–d. 1914). Sea urchins (a.k.a. Sea Hedgehogs or Whore's Eggs) are found in every ocean and every climate, from the tropics to the polar regions, from the sea bed to the shore. The Oxford English Dictionary's earliest evidence for Whore's Egg is from 1674, in the writing of John Josselyn, a travel writer. .

When this map was published:

https://en.wikipedia.org/wiki/History_of_marine_biology

"Between the late 15th century and early 20th century, humans explored the oceans like never before creating new maps and charts and collecting specimens to bring back to their home ports. Most of the exploration that took place during this time was fueled by European countries such as Spain, Portugal, France, Italy, Scotland and Germany. Some of the landmark explorers of marine biology carried out their famous work during this time period. Explorers such as Captain James Cook, Charles Darwin and Wyville Thomson made revolutionary contributions to the history of marine biology during this time of exploration.[19]

James Cook
James Cook is well known for his voyages of exploration for the British Navy in which he mapped out a significant amount of the world's uncharted waters. Cook's explorations took him around the world twice and led to countless descriptions of previously unknown plants and animals. Cook's explorations influenced many others and led to a number of scientists examining marine life more closely. Among those influenced was Charles Darwin who went on to make many contributions of his own.[2]

Route from Plymouth, England, south to Cape Verde then southwest across the Atlantic to Bahia, Brazil, south to Rio de Janeiro, Montevideo, the Falkland Islands, round the tip of South America then north to Valparaiso and Callao. Northwest to the Galapagos Islands before sailing west across the Pacific to New Zealand, Sydney, Hobart in Tasmania, and King George's Sound in Western Australia. Northwest to the Keeling Islands, southwest to Mauritius and Cape Town, then northwest to Bahia and northeast back to Plymouth.
The voyage of the Beagle
Charles Darwin
Charles Darwin, best known for his theory of evolution, made many significant contributions to the early study of marine biology. He spent much of his time from 1831 to 1836 on the voyage of HMS Beagle collecting and studying specimens from a variety of marine organisms. It was also on this expedition where Darwin began to study coral reefs and their formation. He came up with the theory that the overall growth of corals is a balance between the growth of corals upward and the sinking of the sea floor.[20] He then came up with the idea that wherever coral atolls would be found, the central island where the coral had started to grow would be gradually subsiding [21]

Charles Wyville Thomson
Another influential expedition was the voyage of HMS Challenger from 1872 to 1876, organized and later led by Charles Wyville Thomson. It was the first expedition purely devoted to marine science. The expedition collected and analyzed thousands of marine specimens, laying the foundation for present knowledge about life near the deep-sea floor.[22] The findings from the expedition were a summary of the known natural, physical and chemical ocean science to that time

Exploration technology
In the past, the study of marine biology has been limited by a lack of technology as researchers could only go so deep to examine life in the ocean.[27] Before the mid-twentieth century, the deep-sea bottom could not be seen unless one dredged a piece of it and brought it to the surface. This has changed dramatically due to the development of new technologies in both the laboratory and the open sea. These new technological developments have allowed scientists to explore parts of the ocean they didn't even know existed.[28]

The development of scuba gear allowed researchers to visually explore the oceans as it contains a self-contained underwater breathing apparatus allowing a person to breathe while being submerged 100 to 200 feet into the ocean.[29] Submersibles were built like small submarines with the purpose of taking marine scientists to deeper depths of the ocean while protecting them from increasing atmospheric pressures that cause complications deep under water. The first models could hold several individuals and allowed limited visibility but enabled marine biologists to see and photograph the deeper portions of the oceans.[29] Remotely operated underwater vehicles are now used with and without submersibles to see the deepest areas of the ocean that would be too dangerous for humans. ROVs are fully equipped with cameras and sampling equipment which allows researchers to see and control everything the vehicle does. ROVs have become the dominant type of technology used to view the deepest parts of the ocean."