of its proximity to the much bigger island today called Kvaløya, that according to this theory was earlier called "Store Tromsøya" due to a characteristic mountain known as Tromma (the Drum). The mountain's name in Sámi, Rumbbucohkka, is identical in meaning, and it is said to have been a sacred mountain for the Sámi in pre-Christian times.

The Sámi name of the island, Romsa, is assumed to be a loan from Norse - but according to the phonetical