Both. I think it is a peninsula on an island.
A country
Newfoundland is a Canadian province (Province is a state in Canada). Peninsula is supposedly an island.
The island of Cozumel, east of the Yucatan peninsula.
One example of a country that is both an island and has part of its territory on the mainland is Denmark. It consists of the Jutland peninsula as part of its mainland territory and numerous islands, including Zealand and Funen.
Hawaii is an island and a state. It is not a peninsula.
Sumatra
yes, it is between China and the Philippines
No, Spain is not an island. It is a peninsula.
Cuba is an island country in the Caribbean, 42,800 square miles ( a peninsula is a tract of land nearly surrounded by water, an island is completely surrounded by water as is Cuba)
Singapore
Malaysia