The Castrovin Sea is a large, land-locked body of water, which begins near the ancient realm of Iobaria in northwestern Casmaron, and stretches thousands of miles eastward. It borders the lost kingdoms of Ninshabur, Kaskkari, in its western and southwestern reaches, the mighty Kelesh Empire to the south, and fabulous Kaladay to the northeast. Strange island nations, such as ancient Iblydos, can be found along its coast. At least in its northwestern regions, the Castrovin is harsh and choppy, making it difficult to navigate. Sea traffic is generally limited to small fishing vessels which stay close to the coastline. The Castrovin Sea has a generally tempering effect on the climate of Casmaron, increasing rainfall and moderating temperatures along its shores.
The Castrovin Sea is the main waterway for trade for the nations along its shores, and countless merchantmen from Kelesh and other exotic locales can be found making their way along its coasts. This in turn attracts pirates who prey upon the merchants, countered by naval ships of the Empire of Kelesh. All but the most foolhardy sailors, however, avoid sailing into the deeper waters. The central Castrovin Sea is plagued by terrible storms and dangerous rocky islets and sea stacks like Casador's Maw, Citadel Allatro, and the Pillars of Trajheir. These small outcroppings of land are often the domain of tribes of locathahs, and pale-scaled merrows, who exploit the connections of these islets to deep tunnels to the Darklands.
- Erik Mona et al. (2008). Campaign Setting, p. 153. Paizo Publishing, LLC. ISBN 978-1-60125-112-1
- James Jacobs et al. (2011). The Inner Sea World Guide, p. 204. Paizo Publishing, LLC. ISBN 978-1-60125-269-2
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