Simplify the following text for a Grade 9 native English-speaking person.
Original: The four biggest countries that are mainly archipelagos are Japan , the Philippines , the United Kingdom and Indonesia ( the world 's biggest archipelagic country according to the CIA World Factbook ) .
Simplified: The five largest modern countries that are mainly archipelagos are Indonesia , Japan , the Philippines , New Zealand and the United Kingdom . The largest archipelagic state in the world , by size , is Indonesia .