1) The word "mountain" contains three vowels: O, U, and A.

2) The global push for COVID-19 vaccination campaigns has been a significant focus, with the development and distribution of vaccines to combat the spread of the virus and protect public health.

3) The Southern Ocean surrounds Antarctica and is the coldest and least-visited ocean.

4) The Hollywood Walk of Fame features more than 2,690 stars embedded in the sidewalk, honoring notable figures in the entertainment industry.