Swim to shore and head down a hallway

It's a short swim to the shore, and you step up onto the sand, leather clothes drenched and hair dripping with water. You take a quick look around, but decide to simply journey down one of the pathways, and take the leftmost tunnel, which slants upwards slightly.

The tunnel continues upwards for a short while, but before you find another room, you come to a crossroads of sorts. Another tunnel seems to run down, parallel to yours for a while, and so you almost don't notice the turn behind you. Down that hallway, all you can see is a dim glow that seems to pulse in waves along the rock walls, but the other hallway seems more promising- it appears to slant back downwards, and opens up into a well-lit room with a bright green floor.

The dim, pulsing glow makes you pause, but the greenery is more inviting, and so you head further down the tunnel, which quickly opens up into another room, bright and rather small. The walls and floor are green, coated with ivy and grass alike, giving the room a sense of warmth. In the very center appears to be an old well, cracked and faded with time, the base ringed by vibrant flowers. There are a pair of ornate marble benches on opposite sides of the well, seemingly a good place to rest. The only other object of note in the room appears to be a small wooden bookshelf, with a trio of books on its top shelf. Besides the door you've entered from, there's another hallway of a similar size on the opposite side of the room.