The Blue Angel Sea Slug
This bizarre creature is only found around South Africa and Australia. The blue angel is a carnivorous and venomous creature, so don't mess with it, even if it may look like some sort of weird algae.
Blue Lava
The Kawah Ijen volcano in Indonesia spews great volumes of blue and purple lava. Well, at least it appears to be. Due to the sulfur concentration of the land surrounding the volcano, the lava burns a bright blue hue that can be seen from very far away.