The forest cover around Chilika is scanty. Sandy ridges rise at its southern end, closing it up periodically and cutting the lagoon off from the sea. Tidal ingress is felt only along the outer channels parallel to the sandbar. Thus the virtually landlocked lagoon waters are brackish in contrast to the fresh river waters that drain into it and the saline seawater found outside the narrow 200-metre opening into the vast Bay of Bengal. The silt borne down by the rivers has no access to the sea and spreads into the lagoon, promoting a proliferation of weeds that thrive on the rich organic matter. Clay, sand and mud are found at the centre of the lake, while shell-flaked sand borders the marginal areas. Several islands with a total area of 28.53 sq km dot the lake.

Terrestrial mammals are found in the hills, forests and islands around the lake as well as the sandy ridges.

Though birds are seen all over, the maximum concentration is at Nalbana, Gerasara, Bhusandapur, Mangalajodi and Sorana. These areas shelter lakhs of birds that feed and roost here.

Several interesting islands dot the lake and are worth a visit. Beacon Island is so called because of the conical tower standing on a submerged rock. It stands at a distance of 3 km from the Orissa Tourism Development Corporation (OTDC) at Rambha. …Snodgrass, who was once the Collector of Ganjam, used the room on top of the pillar to rest and marvel at the view of the water.

Birds' Island earns its name from the many birds that converge here in winter. It is also known for its algal extravaganza. This one lies 4 km from the OTDC at Rambha. Huge granite rocks with overhanging shelves characteristic of the terrain make attractive perching grounds for the birds. Birds' Island is the ideal location for an amateur birdwatcher interested in a large number of sightings of diverse species.

Barkuda Island is located 5 km away from the Rambha jetty. It is exquisitely pretty with clear, deep-blue waters. The limbless skink was first spotted in the loose soil of the Barakuda islands as early as 1917. You might see one too.

Parikud Islands are a group of islands also called the Garh Krishnaprasad Block, which are an ideal spot for birdwatching in the winters.

Aquatic plants of different varieties are found in the lake and on sandy soils, you will also find Halophila ovalis growing here. The Nalbana Island, which is dry during the summer, reveals tattoos of vegetation patterned on its barren depths.