MADRID — Gibraltar is a narrow peninsula at the southern edge of Spain, dominated by a stunning limestone mass of land known as The Rock.

But it is not an island.

So over the weekend when Gibraltar inaugurated the International Island Games, a competition that gathers athletes from over 20 places, including Bermuda and Greenland, local officials had no clear explanation as to why it was being recognized as an island just for this purpose.

“There is no definitive answer,” said people like Owen Le Vallee, who is from the island of Guernsey and is a founding member of the International Island Games Association, which was set up in the 1980s.

Sports is one of the best ways to get recognition, said an employee at a local duty-free store, and though the territory is not an island, “most foreigners think that this is what Gibraltar is.”