The true size of the Green Sea is unknown - survivors can only ever glimpse a portion of the sea on national maps of Chernarus found at schools and military bases, where it is shown to stretch from the Black Mountains to Takistan. Arma 2: Operation Arrowhead revealed much more of the region, showing the Green Sea stretch as far down as Karzeghistan, and potentially Ardistan, on Takistan's southern border. The Green Sea is also shown to envelop the islands of Skalisty, Utes, Lyutyi and Moschnyi.
The Green Sea has evidently had a profound effect on the countries it bounds - in Chernarus' case, four of the six major settlements in the country, including Chernogorsk and the capital Novigrad, are situated on the coast. Likewise, in South Zagoria coastal regions tend to be the most developed and industrialised, with only a few notable exceptions inland (Novodmitrovsk and Severograd).
In desperate times, survivors can use the coastline as something of a "poor-man's compass" - if the sea is on your right, you are either heading east or north; if the sea is on your left you are heading either south or west. This information, in conjunction with other terrain features, can assist in the process of pinpointing just where one is.
- In reality, the Green Sea is likely the Caspian Sea, as evidenced by Arma 2's official launch trailer, which appears to show that Chernarus is located on the western side of the Caspian Sea, near Georgia and Russia.