The Isla Culatra is a short-ish (35-40 minute) ferry ride from Olhao. The island is composed of fishing boats and piles of netting to the north, sand dunes and ocean-front exposure to the south, and tiny, tiny houses where people get around by golf cart in the middle. Why so tiny, houses?
Not sure, but the island is renowned as a nature preserve with great bird watching opportunities. None presented themselves on our day, a drizzly, grey morning, but I can imagine how fun this island would be in the sunshine.