Sandwich Harbour (Portuguese: Porto d'Ilheo) is a lagoon on the Atlantic coast of Namibia, lying south of Walvis Bay, within the Namib-Naukluft National Park. Formerly a moderately-sized commercial port based around whaling and small-scale fishing, it declined as the harbour silted up, and is now best known for its birdlife. Although called Sandwich Harbour it was never a harbour or even a port. It is a shallow lagoon lying about 80 km South of Walvis Bay. The area was surveyed in the 1880s by the Royal Navy but it was considered very inferior to Walvis Bay and no development took place. Occasional sealing vessels used it as an anchorage, possibly to avoid the authorities at Walvis Bay, and there were some temporary settlements used by seasonal fishermen catching snoek (Thyrsites atun).