The Red Sea represents a complex and unique tropical marine ecosystem with extraordinary biological diversity and a remarkably high degree of endemism.
The sea is the habitat of over 1,000 invertebrate species and 200 types of soft and hard coral, and around 10% of these are found nowhere else.
It is the world's northernmost tropical sea and has been designated a Global 200 ecoregion.

The rich diversity is in part due to the 2,000 km (1,240 mi) of coral reef extending along its coastline; these fringing reefs are 5000–7000 years old and are largely formed of stony acropora and porites corals. The reefs form platforms and sometimes lagoons along the coast and occasional other features such as cylinders. These coastal reefs are also visited by pelagic species of Red Sea fish, including some of the 44 species of shark.
It contains 175 species of nudibranch, many of which are only found in the Red Sea.