Within the entire TEP, two eco-regions were ranked equally and of the highest biological value, the Panama Bight and the Nicoya eco-region. The latter incorporates the Gulf of Chiriquí.

The Gulf of Chiriquí is unique in the TEP due to a combination of features:
(i) consistently warm temperatures due to the lack of up-welling,
(ii) proximity to the continental shelf which provides semi-oceanic conditions with clear water which is suitable for tropical reef fishes,
(iii) an abundance of corals and coral reefs,
(iv) the abundance of coral reef fishes that need structural reefs (rather then just corals), and
(v) a high diversity of large fish fauna.

The Gulf of Chiriquí is also unique for the continental area of the eastern Pacific in having the largest assemblage of Trans-Pacific fishes in the TEP.

The Gulf of Chiriquí has a far greater diversity of marine habitats than the Cocos Islands or the Galapagos National Parks; thus the diversity of fishes is far greater in the Gulf of Chiriquí than the other sites. The Gulf of Chiriquí has 760 species of shore-fishes vs. 449 for the Galapagos Islands and 310 at Cocos Island.

The oceans contain huge schools of fishes, including trans- Pacific shore-fishes which are commonly associated with southern Pacific. This environment is also a key link in the Tropical Eastern Pacific, providing transit for numerous pelagic fish as well as marine mammals.
The property includes 760 species of marine fishes, 33 species of shark and 20 species of cetaceans.

Excerpts from the decision of the 29th session of the world heritage committee: REPUBLIC OF PANAMA. PROPOSAL FOR THE INSCRIPTION OF THE COIBA NATIONAL PARK IN THE LIST OF WORLD HERITAGE SITE OF UNESCO (January 2005).