Poas volcano is located at 2,750 m altitude and has 2 craters one of which is the only crater on the face of planet filled with the sulfurous lake. One crater is still active and from time to time one could see geysers blowing the steam from the face of the lake. Poas is deemed to be a world's biggest geyser. You can see on this image small plum of small sulfuric smoke on the lake . The summit area of Poas Volcano is covered with ash and has little vegetation. Explosions still occur regularly, and the activity like the steam, is often caused by the interaction of the lava with the water. While the water in the lake may seem inviting, it is extremely acidic and can be as hot as 85 degrees Celsius, so it is definitely not for swimming.
79 species of birds live in Poas national park, like hummingbirds and the resplendent Quetzal.

Needless to mention that it's best image of Poas volcano in existence, LOL !