Ballynakill Bay is a coastal bay in County Galway, Ireland, forming part of the Connemara coastline along the Wild Atlantic Way. The bay is situated at the foot of Diamond Hill mountain, with the village of Letterfrack sitting at its mouth, serving as a gateway to Connemara National Park. The bay offers views of the Twelve Bens mountain range. The primary paddling character is defined by its tidal nature and exposure to the Atlantic. The bay fills from Galway High Water minus 0500, and tides are generally weak except at narrow points, indicating that currents are not a major hazard in the open bay but can accelerate in confined channels. As an open coastal bay, it is exposed to prevailing winds and Atlantic swells, which can create challenging conditions, particularly on the outer sections. There is a natural shelter noted at Ballynakill Harbour near Derryinver, which features a pier. This suggests a potential launch or take-out point for paddlers seeking protected water. Derryinver pier itself is a busy place. The surrounding Renvyle Peninsula offers sweeping views across the bay. Paddlers can expect a scenic environment with a mix of mountainous backdrop, islands like the grassy Braadillaun, and historical sites such as the ruins of Renvyle Castle at the peninsula's tip. The area is a known destination for sea kayaking tours.