1) Native American mythology is incredibly diverse, with numerous tribes and cultures across North and South America having their own unique traditions and stories. It encompasses deities, nature spirits, tricksters, and heroes, reflecting the deep connection between indigenous peoples and the natural world.

2) The word "yesterday" contains three vowels: E, A, and A.

3) The word "computer" contains three vowels: O, U, and E.

4) Celtic mythology encompasses the folklore and legends of the Celtic peoples across Europe, particularly in regions like Ireland, Scotland, and Wales. It features deities like Morrigan, Cernunnos, and Brigid, and delves into themes of nature, magic, and the heroic exploits of legendary figures like Cu Chulainn.