Where a lone street of the seaside hamlet of Schoenmakerskop terminates on the edge of a bluff, a solitary bronze cannon aims out over the ocean and a small, secluded bay. It marks the site of an extraordinary shipwreck discovered in 1977. The cannon itself was pulled from the site and dubbed the "miracle cannon" because it remained perfectly preserved despite centuries on the sea floor.

In 1647, the Sacramento, a large Portuguese galleon, was on her maiden voyage. The ship carried a massive consignment of artillery pieces meant for King João IV from the city of Macao (a Portuguese colony in China, at the time), along with silk, porcelain, and spices. During a storm, the over-laden vessel was smashed on the coast's rocks and sank, an ignominious end for a galleon that might otherwise have been a formidable part of the Portuguese fleet.

The 2,500-kilogram (5,500-pound) artillery gun that now marks the site is one of around 40 cannons that were salvaged from the wreck site in 1977. Dubbed the "miracle cannon" because it was so well preserved, it had, according to the salvage team, the same bronze shine upon salvage that it would have the day it was cast. It now has the familiar light-green patina that weathered bronze assumes, but the name of the Bocarro foundry in which it was cast and the Macanese coat of arms are still clearly visible, along with the intricately crafted lifting lugs shaped in a half-human, half-dolphin form.  

The memorial also describes the tragically remarkable story of the 72 survivors of the Sacramento, who struggled ashore and, due to the lack ports on the South African coast at the time, and the slim chances of rescue by passing ships, attempted a perilous, 1,300-kilometer (800-mile) journey to what was then called Delagoa Bay, or modern-day Maputo. Six months later, in January 1648, the nine remaining survivors arrived at Delagoa Bay.