Conwy's layout makes its dependence on sea power visible in the opening diorama. The town has a major port and fishing beach, while the castle controls a separate waterside landing. Important parts of the settlement sit beneath the fortress's fire. Water surrounds the rocky promontory and provides a supply route that a land army cannot close. Taking the town would therefore leave the conquest incomplete unless the attacker also controlled the castle and the sea.
Chapter · 1:36-3:30
Conwy's maritime castle plan
The opening uses Conwy's town port, castle port, promontory, and sea access to show why the castle was built as a maritime stronghold.