The only way to the Perhentian Islands is by catching a boat at Kuala Besut Jetty. A return ticket from here will cost RM70. It does not matter where you take your return boat from, meaning you can arrive at Perhentian Kecil, for example, stay a few days, hop on a sea taxi to Perhentian Besar, and return to Kuala Besut from there.
Sea taxis frequently traverse the narrow strait separating Perhentian Besar and Kecil, and cost between RM10 and RM30 - depending on the distance they have to travel.
During the high season from March to September, boats from Perhentian Besar and Kecil depart at 8am, 12pm and 4pm. In the low season, the 4pm boats are infrequent.