Porto Istana is a series of four small beaches separated by rocky granite headlands, strung out along the coast about 15km north of Olbia. The beaches face directly toward Tavolara — the great limestone monolith that rises dramatically from the sea — and the snorkelling in the shallow water between the beaches and the island is among the best accessible from land in this part of Sardinia.
The water is noticeably calmer and clearer than at Pittulongu because the Tavolara massif shields the bay. Each of the four beaches has slightly different character: the southernmost is the most sheltered and family-friendly; the northernmost is slightly rockier and attracts divers. A road runs along the coast connecting them; parking can be tight in August.