Reen Pier extends thirty metres into the sheltered waters of Bunnaglanna Cove, a natural harbour carved from the southern shore of West Cork where the League River meets the Atlantic. Built in the nineteenth century to serve the fishing villages scattered along Roaringwater Bay, the stone slipway remains the departure point for seasonal whale-watching expeditions that track fin whales, minke whales, and common dolphins along the continental shelf eight nautical miles offshore. The pier's granite blocks, laid without mortar in the traditional dry-stack method, have withstood a century and a half of winter storms; barnacles colonise the lower courses, and at low tide the exposed pilings reveal centuries of tidal wear. Cork whale watch reen pier tours operate from late spring through early autumn, when Atlantic currents bring plankton blooms that draw baleen whales into the nearshore feeding grounds between Mizen Head and the Fastnet Rock. Operators licensed by the Irish Whale and Dolphin Group depart from the pier in rigid-hull inflatables and converted fishing trawlers, following sighting protocols established by marine biologists who have tracked cetacean migration patterns in these waters since the 1990s. The route passes Baltimore's thirteenth-century castle ruins, skirts the uninhabited Carbery Islands, and reaches the deep-water channel where fin whales—second only to blue whales in size—surface to breathe during their northward journey toward Icelandic feeding grounds. The pier itself occupies a triangular plot at the end of a single-track road that winds through hedgerows and stone-walled pastures, three kilometres south of Union Hall village. No permanent structures stand on the pier; visiting boats moor alongside bollards set into the granite, and a narrow shingle beach flanks the eastern side. Local knowledge holds that the pier was extended twice—once in 1902 and again in 1948—to accommodate deeper-draft vessels, though county records were lost in a fire. On clear mornings the Fastnet Lighthouse is visible eleven kilometres to the southwest, its white tower marking Ireland's most southerly point. Whale-watching expeditions from Reen Pier contributed €1.2 million to the West Cork tourism economy in 2025, according to figures compiled by Cork County Council. The pier remains free to access year-round, with no formal facilities; operators provide safety briefings and weather updates at the slipway before departure. Sightings are never guaranteed—marine mammals follow prey, not schedules—but captains report encounters on approximately seventy per cent of summer sailings, a success rate driven by real-time communication between boats and shore-based spotters who scan the horizon from clifftop vantage points above Kedge Island.