It's a park! It's a lake! It's... both?
Just below Austria's Hochschwab mountains near the town of Tragoess sits Grüner See ("Green Lake" in English).
Why do I care, you say? Well, you care because it literally changes with the seasons -- and we're not just talking about leaf colors. During winter, the lake is only three to six feet deep and is surrounded by parkland that is perfect for hiking and exploring.
Winter, for example:
But come spring, as the temperature rises, the ice and snow from the surrounding mountains begins to melt and trickle down into the basin of land below.
By summer (aka NOW), the lake reaches is maximum depth of about 40 feet and the park-turned-lake becomes a hotspot for scuba divers. The lake's green color (hence, its name) comes from the grass and foliage that line the bottom of the basin.
See you there!