Gunwalloe was the site of a wreck on 19 January 1526 when the Flemish ship St Anthony, owned by King John III of Portugal, laden with bullion, plate, and silver, was driven ashore in "an outrageous tempest of the sea." Only forty–five of her crew survived. The local people spent all day and night salvaging silver. Two days after the wreck, three local magistrates, William Godolphin, Thomas St Aubyn and John Millaton, attacked the surviving crew and made off with two–thirds of the bullion. The Portuguese King appealed to King Henry VIII. In answer to these charges, the three men stated that the chief ruler of the ship, fearing the country people helping the salvaging would take it home with them, had begged to the three to come to his aid. They declared that the ship's master entreated them to buy some of'the salvaged goods in order that he could buy some necessities. This is all, they insisted, they took for themselves.

Another 'treasure ship' was lost there in the 1780s. Also Spanish, but unnamed, she struck below the cliffs midway between Gunwalloe Church Cove and the fishing cove half a mile westwards. The ship broke in two and spilled the coins and bullion into a gully. In 1845 a company was formed to dam the gully and pump out the water to recover the money. The night before everything was ready, a gale came up and wiped out two month's work. In 1847 another attempt was made for miners to cut a path and steps down the cliff and sink a shaft twenty–five feet into the rocks, working only in low tide, then driving forty feet under the gully, the idea being that the coins would fall into the tunnel. No coins appeared but the sea did, and the miners barely escaped. The breach could not be sealed.

Storms off of Mount's bay produce vast movements in the sea bottom and periodically thousands of tons of sand can be scoured away overnight. Parts of Gunwalloe Cove can change by as much as twenty feet at a time.