Blue Dagger Lagoon

The Blue Dagger Lagoon is a large inlet of water that cuts into the southern edge of Beru. It acts as the mouth for The Sapphire Run granting easy access to the northern Kingdom of Breaton & eastern frindge of the Mirage Alliance.

Geography

The banks of this inlet are gentle and sandy, with trees and bushes lining either side. The bay experiences a drastic variation in height depending on the tides, with its area shrinking to nearly a third its maximum size on particularly low tides. 
The ground here is a mixture of loose sediment that flows down The Sapphire Run and natural sandstone that forms the base of the south-western portion of Beru. 
Resting on the western shore are the ruins from a civilisation lost to time & on the eastern shore is the settlement of Conchar. 
To the south of the lagoon where it meets the sea is a collection of sandbars and reefs that act as a waterbreak, preventing the violent storms that ravage that portion of Beru from striking further upstream. This is where the water here becomes brackish.

Ecosystem

The lagoon itself is populated by schools of euryhaline fish such as salmon, sawfish and bass. Some sharks can be found here as well as more dangerous creatures that thrive in water. The banks themselves act as a physcial barrier to larger creatures that dwell on either side of the waters, though sailors that traverse these waters tell tales of swimming beasts crossing the gap. 
The weather here is mild for most of the year, but can change quickly due to the low topography.

Ecosystem Cycles

Throughout the year the population and variety of fish found here varies, with the river swelling in the spring. During the seasonal high and low tides the mudflats become exposed or swollowed up by the waters creating inches of clear, brackish water that can be waded into for nearly a hundred feet. 
When the highest tides come the river bursts its eastern banks and floods the Vasugan Marshes with fresher water, this phenomenon is a wonderus spectical as fish swim through the mangroves and banyon trees.

Localized Phenomena

Sailors tell tales of beasts swimming from bank to bank during low-tides.

History

The western bank has ruins of a lost civilisation and has acted as an important trade route for the Kingdom of Breaton & Mirage Alliance.
In 882 a decade long monsoon caused the lagoon to swell to twice its original size, washing away nearly half of Conchar in the process.

Type

Gulf / Lagoon