Are OFP's island maps based on real islands?
The original OFP version's three main islands are based on actual existing islands. Kolgujev is based on Tenerife Island, one of the Canary Islands. Everon is the Crotian Island of Krk. Malden is the Greek Ionian island, Levkas. OFP's desert Island is Meganissi, the largest island just to the east of Levkas.
While these islands are based on real islands, the geographical size of OFP's islands in the game are on a smaller scale than the real ones.
Unlike Malden, Kolgujev and Everon, OFP: Resistance's island, Nogova, is almost pure fiction. I say almost because, while the island as a whole is imaginary, some of the locales on Nogova have the same or similar names and landmarks as real places in the Czech Republic. For details, read the article "Nogova and Reality" at OFP.CZ.
With thanks to master addon maker Kegetys, squadmate Veit and OFP player MarcusJClifford for providing most of the information here.
OFP's Kolgugev and Tenerife
OFP's Everon and Krk
OFP's Malden and Levkas
OFP's Desert Island and Meganissi (East of Levkas)