When it comes to beaches, the volcanic islands of Hawaii aren't content to leave it at sugar-white. They mix it up with ebony black, Mars red - and green! Papakōlea's not exactly blazing emerald, but it does have a distinct green tint from olivine crystals deposited on the beach by a volcanic explosion about 10,000 years ago. These crystals are heavier than the rest of the volcanic materials, so as the water washes the rest away, the beach gets greener. Eventually the olivine will run out and the beach will be grey, but not any time soon in human terms.