Bantry Bay is a ria - a coastal valley flooded by rising seas after the last Ice Age. The bottom is deep, about 40 metres in the middle, which is why it has become Ireland's principal petroleum harbour. The bay runs roughly northeast to southwest into the Atlantic, three kilometres wide at the head and ten kilometres wide at the entrance. The Beara Peninsula forms the northern shore and the Sheep's Head Peninsula the southern. Two islands sit inside: Bere Island, near the entrance, hosting Berehaven Harbour and the port of Castletownbere; and Whiddy Island, near the head, hosting the deep-water Whiddy Oil Terminal. Towns and villages ring the shore - Adrigole, Castletownbere, and Glengarriff on the north side; Bantry itself at the head; Ballylickey and Donemark close by. The N71 runs along the bay's southeastern edge, while the R572 traces part of the northern Beara coast as the Ring of Beara. Dunboy Castle, the ancestral seat of the O'Sullivan Bearas, stands across from Bere Island in Berehaven, with Copper John Puxley's nearby manor giving Daphne du Maurier the setting for her 1943 novel Hungry Hill.

Bantry Bay's first famous battle came in 1689, during the Nine Years' War, when English and French fleets clashed at the bay's mouth - a Jacobite-era engagement that ended inconclusively. The more consequential moment came a century later. In December 1796, the French Republic sent General Lazare Hoche with 15,000 troops and forty-three ships to land at Bantry Bay, link up with the Society of United Irishmen, and detach Ireland from British rule. The expedition was Wolfe Tone's project; he sailed aboard the Indomptable. Bad weather and worse coordination scattered the fleet. The flagship Fraternite carrying General Hoche was driven off course. The remaining ships rocked at anchor for almost two weeks, unable to land because of relentless gales. Local landowner Richard White marshalled the militia along the shore in case the French got off the ships, and would later be rewarded with the title Baron Bantry for his trouble. The French gave up and returned to Brest, having lost twelve ships and over 2,000 men without a single soldier setting foot on Irish soil. The town square in Bantry is named for Wolfe Tone today. The wreck of one of the lost French ships, the frigate La Surveillante, scuttled in the bay on 2 January 1797, was discovered in 1981.

On the night of 8 January 1979, the French oil tanker Betelgeuse was discharging her cargo at the offshore jetty of the Whiddy Island oil terminal when she caught fire, exploded, and broke into three pieces. Fifty people died - 42 French crew members, seven Irish dockworkers, and one British diver who would die later during salvage operations. The cause has been argued ever since; an Irish tribunal report later attributed the disaster to corrosion-weakened tanks and shortcomings in fire response. The Betelgeuse Memorial stands in St Finbarr's Church graveyard in Bantry, overlooking the harbour. Fifty names face the water. The oil terminal continues to operate today, run now by Zenith Energy through a Single Point Mooring, but the disaster reshaped Irish offshore safety regulation and remains the deadliest industrial accident in County Cork's history. The bay has had numerous shipwrecks over the centuries; that one is the one that everyone remembers.

In a strange footnote to all this maritime drama, Bantry Bay turned up on American television screens during the most-watched moments in human history. In 1969, around the time of the Apollo moon landings, a Gulf Oil commercial featured the supertanker Universe Kuwait at the Whiddy terminal. American viewers learned the name of an Irish bay between footage of astronauts. The Bantry Bay Golf Club sits at the head of the bay across from Whiddy Island. The Bantry Inshore Search and Rescue Association runs a high-speed RIB lifeboat from Bantry Harbour, a declared resource of the Irish Coast Guard. The Bantry Longboat - a small French scouting boat that landed on Bere Island during the 1796 expedition and was forgotten in the harbour for 102 years - is now preserved at the National Museum of Ireland at Collins Barracks in Dublin, restored at a cost of 50,000 euros. The bay still holds all of this. Most days it just holds the weather, the fishing boats, and the long blue light of an Atlantic inlet.