You could rather say: "Indonesia is surrounded by the ocean." Its not common to use area in that sentence. If you want to use the word area rather replace it with parts. "Many parts of Indonesia are in close proximity of the Ocean". But: "The police cordoned off an crime scene area." or "They are measuring the square meterage of the area."

Selamat pagi. I have only been to Bali 4 times. I love it here.