RAJABORI VILLAS - KOH TRONG - The King's Island
It's really easy ; one must go to the Port of Kratie, in front of Santepheap hotel and there wait for the wooden boat that work as a ferry.
It costs 1000 riels per passenger and the crossing takes about five minutes.
To leave the island it's the same, one just has to wait on the beach, or in front of the pagoda in the rainy season when the water level is high.
When coming to stay on the island with a lot of luggage, it is slightly more complicated...
The best thing is to ask your guesthouse to organize the transfer from the peer on the island with an ox(or horse)cart (5$ one way), a moto-taxi (1$ one way) or the only tuk tuk on the island (5$ one way) to come pick you up or even organize a direct transfer by private boat (10-15$ one way) to the foot of your selected accommodation (in the rainy season only as the beaches that uncover in the dry season render that impossible).