From the Overgrown Pool area heed the following directions:
- Northwest (to reach empty node, can cross river to the south)
- West (path loops 180 degrees)
You probably won't detect your destination, Three-Pine Islet, until you reach the end of the last step. Once you do, however, you'll be able to enter.
Do so and you'll find yourself along the southern end of the Three-Pine Islet area map, with running water to the north. Turn east and make your way to an area transition, near which you'll find three of the beasts that plague this area: Tatzlwyrms. Cut them down and be wary of their poison, then ford the river to the north of the area transition.
Across the water you'll find a small stone pillar beyond (north of) which more Tatzlwyrms lurk. Stay well clear (west of) this pillar, as around it there's a trap [Perception 20], which probably can't safely be disarmed [Trickery 20] until you get rid of the Tatzlwyrms. Do so, but be wary of yet another trio of Tatzlwyrms that lurk to the west, which may well join the battle if you tread too near them. Once the reptiles are dead and the trap has been disarmed you can get to looting.
Loot the (formerly) trapped pillar to find some coins and a Scorched Fragment of a Necklace, then pass two [Perception 8] checks to note stones you can search in the ruins to the west and north. Both hide some trinkets and a potion. You can also find a spear stuck into the ground near some trees (just to the west of the northern-most hidden lootable). Grab it to score a Longspear +1.
To finish this area up, make your way northwest to find an abandoned row boat, on which you'll find some food and the Recipe: Rice-n-Nut Pudding.
If you're engaged in the Verdant Chambers Expedition, your next stop should be the Ruined Watchtower, which is significantly more involved than the other areas you've visited thus far.