The Algonquin Trail is the most demanding and most scenic route to the summit of Sandwich Dome (3,950 ft), ascending roughly 4 miles and 2,700 feet through the Sandwich Range Wilderness from a trailhead on Sandwich Notch Road. Its place on the Terrifying 25 is earned by a series of ledge scrambles across the open face of Black Mountain, including at least one move difficult enough that no bypass exists. The trail is rough and steep throughout, with slippery rock slabs wherever moisture collects, and the bypass options that do exist for some scrambles can be harder than the direct lines when pine needles are wet.
Because the trail lies entirely within a designated Wilderness Area, there are no blazes; small cairns mark the route across the open ledges, but these are easily buried or obscured in snow. Navigation demands attention throughout, particularly on the upper headwall where multiple ledge bands present choices that are not all equal. A north-facing viewpoint just above the Black Mountain Pond Trail junction rewards the effort with a broad sweep taking in Welch-Dickey, Acteon Ridge, Tecumseh, and the Osceolas.
Access adds its own challenge: Sandwich Notch Road is a narrow, rough track that rewards high-clearance vehicles, and parking at the trailhead fits only a handful of cars. In winter and early spring, ice on the ledges and buried cairns make the upper section especially hazardous; hikers should carry traction devices and navigation tools regardless of season.
