Simplify the following text for a Grade 6 native English-speaking person.
Original: The main city of Ulleungdo is the port of Dodong , which serves as the main ferry port between Ulleungdo and the Korean mainland .
Simplified: In Ulleungdo , there are 3 ç 5 å . In Ulleungdo , there are no thieves , no environmental pollution , no snakes .