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The speed readout on a jetliner's seatback screen uses a unit born from sailors throwing a weighted wooden chip over the stern. The chip log floated upright to anchor itself in the water while the ship pulled away, and a sailor counted knots tied every 47 feet 3 inches in the line as it ran out over a 28 second sandglass. That count works out to within about 0.02 percent of today's international k...

In August 2014, 500,000 people in Toledo, Ohio were told their tap water was toxic and could not be drunk or even boiled for safety, all because of a harmful algal bloom. Scientists are phasing out the term red tide because blooms can be green, brown, or yellow, can be invisible, and have nothing to do with tides. The main culprits are freshwater cyanobacteria, which are bacteria rather than algae...

The black gondola that stands for timeless Venice is largely a 19th century redesign shaped by tourists. Built for a lagoon of shallow mudflats and deep channels, it has a flat, keelless bottom that can slip sideways, and a single unfastened oar that is rowed, not poled. The hull is deliberately lopsided, wider on the left, to counter one rower on the right, and the walnut forcola works like a gea...

On March 18, 1967 the supertanker Torrey Canyon, bound from Kuwait to Milford Haven, slammed into Pollard's Rock on the Seven Stones Reef off Cornwall. Built in the U.S. in 1959 and cut in half in Japan to double its capacity to 120,000 tons without bigger engines or rudder, it was owned by a Union Oil subsidiary, chartered by BP, and flagged in Liberia. Racing to make high tide without full chart...

The RMS Titanic's hold carried a jeweled Rubaiyat of Omar Khayyam and a painting later valued by its owner at $100,000, yet the ship had no searchlight because British merchant rules banned them. It grew from a 1907 meeting between White Star chairman J. Bruce Ismay and financier J.P. Morgan, who were losing ground to Cunard's subsidized Lusitania and Mauretania. White Star chose size and luxury o...

Ernest Shackleton's Imperial Trans-Antarctic Expedition of 1914 aimed to cross Antarctica on foot, and its ship began life in Norway as the Polaris, a polar tourist yacht with ten cabins and a darkroom that went unsold after its Belgian and Norwegian backers fell out. Shackleton bought it cheaply and renamed it Endurance after his family motto. Its keel was over 85 inches of stacked oak and its bo...

Saturation divers live under pressure for weeks, commuting to the seafloor in a sealed bell and spending more than a week decompressing when the job ends. The method rests on a 1942 insight by U.S. Navy medical officer Albert R. Behnke: after roughly 72 hours the body's tissues hold all the inert gas they can, so decompression time stops growing. The first intentional saturation exposure came in 1...

European sailors were marking their skin at least 200 years before Captain James Cook's 1769 visit to Tahiti, which only gave English the word tattoo from the Polynesian tatau. Sixteenth century Mediterranean crews pricked crucifixes and lovers' names into their arms, and 1720s newspapers in Virginia and Maryland described blue initials made with gunpowder or soot. The marks had grim practical use...

SOS does not stand for save our souls or save our ship. It was chosen for its rhythm: three dots, three dashes, three dots sent as one unbroken signal. Before wireless telegraphy in the late 1890s, ships at sea had only flags, flares, and foghorns. Early spark gap radio brought a new problem, corporate rivalry: the Marconi Company forbade its operators to answer ships using competing equipment. In...

Polynesian navigators crossed and settled a Pacific larger than Russia and North America combined without compass, chart, or instrument. The expansion traces to Austronesian speakers from near Taiwan and the Lapita culture, whose stamped pottery spread 6,000 kilometers east to Tonga and Samoa between about 1300 and 900 BC before vanishing on clay free atolls. Navigation knowledge was a guarded, ch...

Franklin D. Roosevelt called it a dreadful looking object and Time dubbed it an ugly duckling, yet American yards built 2,710 Liberty ships during World War II. The design began with a 1940 British order for 60 coal fired Ocean class tramp steamers from a Sunderland plan. The U.S. Maritime Commission reworked it as the EC2-S-C1, switching to oil, welding the hull instead of riveting, and choosing...

On a typical classroom wall map Greenland looks about as big as Africa, which is actually 14 times larger. That distortion comes from Gerardus Mercator's 1569 world map, printed on 18 sheets and explicitly corrected for the use of sailors. Portolan charts worked in the Mediterranean, but on the open Atlantic a straight line on flat parchment drifted off course. Mercator's math turned rhumb lines,...

Born in 1913 in Maxton, North Carolina, Malcom McLean had no money for college, so he bought a used truck and founded McLean Trucking with his brother Jim and sister Clara, hauling empty tobacco barrels. Waiting for hours at ports, he watched longshoremen load break bulk cargo piece by piece at about $5.86 per ton while ships sat idle. His first idea, rolling whole truck trailers onto ships, waste...

An icebreaker does not ram through frozen sea like a battering ram. Because sea ice resists compression but has low bending strength, the ship slides its sloped bow up onto the ice and lets its own weight snap it from above, then its hull shape shoves the broken blocks aside or underneath to protect the propellers. The problem is old: a barge cleared the town moat in Bruges in 1383, and during the...

In the summer of 1919 Alexander Graham Bell's HD-4 tore across Bras d'Or Lake in Nova Scotia at 71 miles per hour, its 10,000 pound hull held clear of the water by underwater wings and pushed by two 350 horsepower Renault aircraft engines. A hydrofoil works because water is nearly a thousand times denser than air, so a small foil can deflect water down and use Bernoulli pressure differences to lif...

In December 1872 HMS Challenger left Portsmouth as a stripped down Royal Navy warship with 15 of its 17 guns removed to make room for chemistry and natural history labs. Backed by the Royal Society of London, and driven partly by the need to lay transoceanic telegraph cables insulated with gutta percha, the voyage covered 68,890 nautical miles between 1872 and 1876, mostly under sail with coal rat...

Fridtjof Nansen was a 12-time Norwegian cross-country ski champion who refined his technique by studying Telemark skiers. After a sealing voyage to the Arctic in 1882, where his ship was trapped in ice off Greenland, he took a post at the Bergen Museum, sliced hagfish spinal cords, and became one of the first scientists to defend the neuron doctrine against Camillo Golgi's reticular theory. He the...

Freediving turns the absence of breath into a survival skill and a sport. Ancient Greek sponge divers rode a skandalopetra stone of up to 15 kilograms to depths of about 30 meters and were hauled back by a partner. In the Peloponnesian War, divers slipped under blockades to carry messages and supplies, and at the Siege of Tyre in 332 BC they cut the anchor cables of Alexander the Great's ships. Ja...

Peruvian fishermen named El Nino after the Christ child because the coastal water turned warm and the anchovies vanished around Christmas. The El Nino Southern Oscillation, or ENSO, is a coupled conversation between ocean and atmosphere. In the neutral state, trade winds push the sun-warmed surface of the Pacific west until sea level near Indonesia sits about a foot and a half higher than off Peru...

In 2012 teenager Boyan Slat took a TED stage with a sketch of a passive barrier that would let ocean currents sweep plastic into its arms, delighting the public and drawing eye rolls from oceanographers. He founded The Ocean Cleanup in 2013 and raised 2 million dollars through crowdfunding in 2014 for a 100-kilometer barrier moored to the seabed with a conveyor belt. Testing ran through 273 scale...

Scrimshaw began on 19th century whaling ships, where men endured months of empty horizon between hunts. Carved from sperm whale teeth, bone, baleen, and sometimes walrus tusks, it started in the late 18th century as practical tools and grew into detailed art made by scrimshanders. The word's origin is unknown, and its first written appearance is an 1826 entry in the logbook of the brig By Chance....

When Spanish galleons entered the Pacific, a priest aboard called them sluggish lead weights beside local boats that flew across the water like birds. The outrigger solved the conflict between speed and stability: a long, narrow hull cuts form drag, and a float on booms supplies the balance a wide hull would. It likely emerged around 1500 BCE among Austronesian-speaking peoples of island Southeast...

In 1878 engineer Henry Fleuss built the first commercially practical closed-circuit rebreather: a rubber mask, a breathing bag, pure oxygen from a copper cylinder, and rope yarn soaked in caustic potash to scrub carbon dioxide. It gave up to three hours underwater with no bubbles, so British, Italian, and German frogmen adopted the technology in World War II. In the US, Major Christian J. Lamberts...

In 1554 French physician Guillaume Rondelet labeled the great white Lamia, after a child-eating monster of Greek myth, centuries before Peter Benchley's 1974 Jaws. The real animal is the sole living species of Carcharodon, a mackerel shark with a strikingly stable genome, reliably measured to about 6 meters and 2,500 kilograms, with females far larger than males. It is partially warm-blooded, warm...

Kelp is not a plant. It is a brown macroalga in the kingdom Protista with no roots and no vascular plumbing: the holdfast only anchors it, the flexible stipe gives it structure, and each frond absorbs nutrients straight from the water while gas-filled pneumatocysts lift it toward the light. Fed by cold upwelling water, giant kelp grows 30 to 60 centimeters a day. Kelp forests and coral reefs cover...