Ostellian Loch

The Ostellian Loch is the largest inland body of water in Ostelliach and, as its name would imply, is hugely important to the land's geography, as it is the creation point for the Broadlysle River. This river winds through much of the continent, including splitting into the Rivers of Grave & Charity, feeding both the Sullen Tributary and Fugue Wisps, and creating many underground water tables and streams that supply both topside and Demoor settlements with water.
The loch is incredibly deep and known for its extremely clean water (thanks in part to fervent efforts by conservationists). The good quality of herbs and plants in the Everglen that supply much of Ostelliach with medical remedies and potion ingredients are often attributed to their proximity to the loch.

Ecosystem

The loch is full of a truly staggering amount of biodiversity, including some types of flora and fauna found only in its waters. The systems and cycles the loch's wildlife experiences are deeply interconnected and often fragile, meaning extreme caution is taken to not disrupt any part, lest it have far-reaching consequences to the food chain, life cycles, habits, and survival of others in the biome.
A good example of this is the special kind of irridescent perch (fish) found along the loch's shorelines. Once prized for its shimmering scales (useful in cosmetics as well as illusion-related potions), overfishing around 250 AB caused disasterous results as the perch was the sole consumer (and inhibitor) of a type of parasitic lichen that then crippled other fish populations for nearly 15 years, before conservationists could properly reintroduce the irridescent perch and restore balance.

Climate

The loch is located in the temperate region of Ostelliach known for the Everglen, where the weather stays moderate for much of the year.
That said, localized monsoons are known to occur in late Baff restores the water of the loch after summer when drought and some hot days may impact the water level. These monsoons typically last 2-3 weeks and are presaged by a local festival full of rain dances and songs (some magical, some mundane) and celebrated after they leave with another festival known for being the one time of year that fishing is allowed in the loch (with special permits granted and closely monitored participation).

Tourism

Conservationists and biologists are the most common visitor to the loch, as recreational activities such as swimming, fishing, boating, or diving are closely regulated and often limited to only certain times of year (such as after the annual monsoons). That said, the loch is beautiful and many traveling through the Everglen or toward Red Flagon will at least stop to admire the massive body of water, camping along its shores before resuming their travels.

Type

Lake