The fort's design is dictated entirely by the rock it sits on. The lower battery occupies two positions: one facing south, the other west. The west position still holds a mortar, along with a water cistern and powder store -- the essentials for a garrison that could not retreat. The summit battery, reached by the upper portion of the 255-step staircase, holds four cannons and a mortar amid the ruins of the officers' quarters. From the top, the view sweeps across Calliaqua Bay, Young Island, and the open Caribbean. The fort was built by the French before 1763, when the Treaty of Paris transferred Saint Vincent to British control. The British maintained and armed it, recognizing that a fortified volcanic plug guarding the southern approach to Calliaqua -- then the island's commercial hub -- was worth the considerable trouble of keeping it supplied.

In 1795, during the Second Carib War, the fort proved its worth in the worst possible way. A British convoy moving supplies along the coast was attacked by Kalinago fighters and overwhelmed. The engagement was devastating: around 60 men from the convoy escort were killed or taken prisoner, and the supplies were lost. The convoy's commander, Ritchie, was mortally wounded while leading the survivors in a fighting retreat to a defensive position. Fort Duvernette's garrison played a role in saving what remained of the convoy's personnel, providing a fortified refuge that the Kalinago could not storm. The episode illustrated both the fort's tactical value and the ferocity of the resistance that the British faced from the island's indigenous population, who were fighting to defend their homeland against colonial expansion.

The fort ceased to have a military purpose by 1878, and in 1971 the site was handed to the St. Vincent and the Grenadines National Trust. The volcanic plug that once made the position so defensible now makes it an ideal wildlife habitat, isolated from the disturbances of the mainland. Scaly-naped pigeons roost in the old gun positions. Blue herons nest on the ledges. Ospreys -- known locally as sea hawks -- hunt from the summit where British officers once scanned the horizon for French sails. In the waters below, Tripneustes ventricosus sea urchins graze through beds of seagrass that have colonized the shallows around the plug's base. The fort was reopened to visitors on May 19, 2011, after restoration work costing 100,000 Eastern Caribbean dollars.

The same qualities that made Fort Duvernette a formidable military position make it a hazardous tourist attraction. The 255 steps are exposed and steep, the volcanic rock is unforgiving, and the sea churns around the base. The fort was closed for repairs in August 2022 due to dangerous conditions. In August 2023, during the closure period, a Nigerian medical student died after slipping from a rock and falling into the sea while trying to reach the fort from Young Island. The site was closed again over safety concerns in January 2025. Fort Duvernette endures in the tension between its magnetic pull and its genuine peril -- a place that people will always want to climb precisely because it was built to be nearly unclimbable. The cannons still point out to sea, and the steps still go straight up, and the volcanic plug does not care whether you are a British marine or a tourist with a camera.