At the seaward end of Postup, near the village of Mokalo, lies the submerged wreck of the Boka, a small Montenegrin steamship. It rests in relatively shallow water, making it accessible to both divers and confident snorkellers. The wreck is encrusted with marine life and provides a slightly eerie contrast to the wine tourism on the slopes above.
Local dive operators based in Orebić can arrange guided dives. The surrounding water is clear and warm in summer, and the wreck sits in a bay that also has decent swimming.