Laacher See is a big lake in Germany that was formed by a volcano a really long time ago. Volcanoes are like big mountains that can explode and throw hot rocks and lava everywhere. When the volcano near Laacher See exploded, it made a big hole in the ground that later filled with water and formed the lake we see today.
Sometimes, the volcano near Laacher See still sends out little earthquakes and gas that come up from underground. These things can make the people who live nearby a little worried, but scientists are always watching to see what's happening and make sure everyone is safe.
Overall, Laacher See is a really cool lake with an interesting origin story involving a big, powerful volcano!