Portugal runs out of coastline here, and it does it gently. Praia de Santo António is the last beach before the Guadiana hands the shore over to Spain — a long, flat run of pale sand between Monte Gordo and the river mouth, backed not by cliffs but by dunes and the pine forest that separates it from Vila Real de Santo António. No rock arches, no drama: the appeal is space, warm calm water, and light that feels bigger than anywhere else in the Algarve.
The border is the photograph. Ships slide in and out of the Guadiana on their way upriver, and across the mouth the low white line of Isla Canela marks another country. Walk east far enough and you are standing on the corner of the map — sand ahead, Spain across the water, pines behind.
When to go: this is the sunrise end of the Algarve. The beach looks out over open water to the east, so first light comes up over the river mouth with nothing in the way. Summer brings the eastern Algarve’s warmest, calmest sea; out of season you can walk for an hour and count the other people on one hand.
Who it’s for: walkers and sunrise shooters who want horizontals instead of cliff drama; families who would trade rock pools for warm, easy water; anyone finishing an east-to-west Algarve trip at the literal end of the line.