This looks like the underground dwelling of the Tuatha de Danaan, or "Children of Danu", the mythological mother goddess of the Irish Celts. Creatures such as leprechauns and other Fairy Folk were known to inhabit these places, particularly under the burial mounds, which were also known as the fairy mounds for that reason.
Fjord-du-Saguenay National Park situated in Québec, Canada is one of the largest & southernmost in the world. The irregular landscapes & breathtaking biodiversity give the area its unique character. Activities in the park include over 100 km (62 mi) of hiking trails, 50 km (31 mi) of skiing trails, camping, kayaking, a Bateau Mouche tour of the fjord, snowshoeing & ice fishing. Accommodations at the park include cabins, huts & campgrounds