Mariaholmen is an islet in Nathorst Land at the mouth of Van Mijenfjorden at Spitsbergen, Svalbard. It is located south of Akseløya, between Akseløya and Måseneset. While Akselsundet north of Akseløya is regarded as the main entrance to Van Mijenfjorden, Mariasundet between Mariaholmen and Måseneset is also navigable.