1) The word "oxygen" contains two vowels: O and E.

2) The national animal of Canada is the beaver.

3) The Plitvice Lakes National Park, situated in Croatia, is a stunning natural wonder known for its cascading lakes, waterfalls, and vibrant turquoise-colored waters. It is a UNESCO World Heritage site and attracts visitors who come to explore its picturesque trails and scenery.

4) The world's largest particle accelerator, the Large Hadron Collider, is located near Geneva, Switzerland, and spans a circumference of 17 miles (27 kilometers).