The waters around Portstewart abound with marine life and shipwrecks, offering fantastic diving. Aquaholics runs PADI-accredited introductory courses (£89) and Open Water courses (£479), as well as dives (from £54, with gear from £80) to locations including Skerries Cavern and HMS Drake near Rathlin Island. Also offers boat trips to Rathlin Island (two-hour trip from £30) and beyond.