Marktosis, also spelled Maaqtusiis in the Nuu-chah-nulth language, is one of the principal settlements of the Ahousaht First Nation, located off the west coast of Vancouver Island in British Columbia, Canada, just southeast of the Hesquiat Peninsula on Flores Island. Accessible only by water or air, Marktosis is a small community predominantly composed of First Nations people from the Nuu-chah-nulth nation. Marktosis has approximately 900 residents. Marktosis Indian Reserve No. 15 was established around the site of the community.
In the neighbourhood is the Clayoquot Sound, a UNESCO Biosphere Reserve.
The nearby communities include:
Coordinates: 49°17′00″N 126°03′00″W / 49.28333°N 126.05000°W