Queen Emma's bath is a tide pool carved into lava shelves below cliffs in Princeville, Kauai. Queen Emma was consort to Kamehameha IV from 1856 to his death in 1863. Her full name was Emma Kalanikaumakoamano Kaleieonalani Na'ea Rooke. She was the mother of Prince Albert, which is where Princeville got it's name. Whether she actually visited this tide pool or if it simply named for her is debated, but the view is spectacular regardless.
During the winter months, this area can be dangerous due to the rough swells of the North Sea. There have been 23 drownings to date. When visiting this site, go during the summer and in between low and high tide for the best snorkeling experience.