The Thousands Islands are a wonderful experience. When you go to this place (Sepa Island) you will see many islands on the way and you will believe that there might be 1000 islands in the area,All the islands have different things to do and see and you need to check that out with your tour operator. The timings also vary a lot to reach these islands.
The beaches seems to be out of your dreams. It is just not possible to explain it in words.
Clean beach, Clear water and Peaceful (if you not there in weekends or holidays). It seems like a private beach all to your self.
If you love beaches and water then this is a must.
One caution - The sea becomes really wild in the afternoons (after 2 pm) and the ride back can be very bumpy.