Sandoy is one of the best islands in the Faroese archipelago for walking — not because of dramatic vertical terrain (the other islands have more of that) but because of the quietness. The trails around Sandur and across Sandoy's interior run through pastoral farmland, along coastal cliffs, and across moorland with views to the surrounding islands and ocean.
The trail north from Sandur along the west coast to the viewpoints above the fjord takes two to three hours and is unmarked but straightforward in clear weather. The route to the lake at Gróthúsvatn and back is an easier half-day walk. Navigation apps with offline Faroese map data work well on Sandoy; the island is small enough that most routes are improvisable for confident walkers. Faroese weather is changeable regardless of season — always carry waterproofs and an extra layer.