1) The word "piano" contains three vowels: I, A, and O.

2) The Dead Sea, located between Jordan and Israel, is the lowest point on Earth's surface. Its saltwater is so dense that people can easily float on its surface.

3) The Indian Ocean is the third-largest ocean and is characterized by its warm waters and diverse marine life.

4) The Grand Canyon, located in Arizona, United States, is a massive and awe-inspiring natural formation carved by the Colorado River. It is approximately 446 kilometers (277 miles) long, up to 29 kilometers (18 miles) wide, and reaches a depth of over 1.8 kilometers (1.1 miles).