On the first night, we decided to go out and explore the island. Unfortunately, there were many dogs, most of whom were incredibly aggressive. Side note: on a later day I was nipped hard by one of them, for absolutely no reason at all. I think they were not so used to foreigners, and had nothing to do. Anyhow, on the first night we found ourselves surrounded by a pack of these barking, howling beasts. Sure we were going to be eaten, we made a quick escape into some random people's backyard, where a barbecue was taking place. They welcomed us with open glasses of Thai whiskey and a cheap acoustic guitar which, to their amusement, I played. We were treated like celebrities; many of them insisted on having photos taken of themselves next to us. I think some Thai people got a lot of likes on Facebook.
Day two. After hiking up a mountain, we discovered a hidden beach. It wasn't hidden in the way that nobody was there; in fact, a decent number of people graced the sand. Rather, it only became visible after we trekked far down the mountainside. We could easily have missed it, but thankfully we didn't! The ocean waves were powerful and rapid. Swimming was incredibly fun, and we didn't leave until it began to rain.
On day three, we shared the cost of renting a motorbike. Both of my companions had driven cycles before, and rode us to the beach. The next morning, before leaving the island, they gave me some lessons (the bike was semi-automatic, and I didn't even have a driver's license), and I drove a motorbike for my first time! A little more practice, and perhaps I'll have a new mode of transport for other parts of my trip!
Almost everything about the trip was top notch: the delicious seafood, beautiful nature, cool beach, and friendly locals. The only bad thing about the island was the dogs, who were way too aggressive for their own good. Bangkok has some really cute, friendly dogs, but for some reason Ko Si Chan was full of bored, neglected savages.
If most islands in Thailand are similar to Ko Si Chan, I cannot recommend isle stays enough.