Madagascar
If you meant 18 degrees north latitude and 77 degrees west longitude, then the island is Jamaica. And, Nairobi is the capital of Kenya, and Kenya is not an island. Kenya is located in Africa.
An island located at 14 degrees south latitude and 173 degrees west longitude is Samoa, specifically the island of Upolu. This island nation is located in the Pacific Ocean, known for its lush rainforests, waterfalls, and vibrant culture.
The point "zero latitude / zero longitude" is located about 380 miles south of Accra, Ghana, in the Gulf of Guinea. There's no land there at all.
Iceland.
The island of Hawaii.
Gotland, the largest island in the Baltic Sea.
San Nicolas Island is located at 33.2500 degrees north and 119.5000 degrees west.
Bornholm, a Danish island.
Riesco Island, Chile.
The Bahamas.
Philippines
There is no island located at these coordinates. The Free and Sovereign State of Sonora in Mexico is found here.