This is the Great Blue Hole of Belize in Central America, and at 300 metres across and 124 m deep, it's thought to be the largest submarine cave on Earth. It was first discovered by French explorer Jacques Cousteau, and was formed over a period of around 140,000 years when the sea levels were much lower than they are now. As the sea levels rose, a number of limestone caves were flooded over time to create this almost perfect circle. It's now home to several species of fish and reef shark. ...

These are rainbow eucalyptus trees (Eucalyptus deglupta) and they hail from the Philippine Islands.

The trees get their name from the striking colours observed on their trunks and limbs. Although it may look like someone took a paintbrush to them, these colours are entirely natural. Unlike most trees, the rainbow eucalyptus does not have a thick, cork-like layer of bark on its trunk. The bark is smooth and as it grows it 'exfoliates' layers of spent tissue. This exfoliation technique occurs at different stages and in different zones of the tree.

Once a layer is shed, a new fresh green bark is exposed. As this new bark ages, we can see the tissue change colour to dark green followed by a bluish colour, then to purple and pink-orange and then f ...

Blue whales are not only the largest animal alive right now, but they are believed to be the largest animal that has ever lived.

They are listed as endangered by the IUCN, but a group of researchers hopes to designate 10% of the ocean as protected by 2020. Despite their slow reproduction times, researchers believe this will be enough to help rebound their number

Belugas apparently fashion their own entertainment by creating bubble rings and then catching them. A beluga at Sea World Kamogawa, near Tokyo, was snapped in the act, and another at the Shimane Aquarium has been seen performing the trick.

Waardenburg Syndrome is a rare autosomal genetic disorder that has possible bright blue eyes as one of its qualifying criteria, along with possible deafness (common). Actually, the cause of the blue eyes is a form of albinism that may include patches of non-pigmented skin or forehead hair, regardless of ethnicity.

There are four types of Waardenburg Syndrome, with a mix of possible characteristics as the determinant. Medical challenges increase with type. The boy in the picture is displaying two major symptoms of type 1; bright blue eyes and dystopia canthorum, a condition where the inner corners of the eyes are set more widely apart, but with normally distanced eyes. ...

Potoos are a small New World family of solitary and nocturnal birds. Most are so poorly known they seem more fiction than substance, their gruff or wailing cries ghostly delusions of the dim nocturnal world they inhabit.

Hummingbirds, like this little golden rufous hummingbird, have up to 1,500 feathers, which is the fewest number of feathers of any bird species in the world.