• 湾わん — a bay; gulf; inlet
• 湾岸わんがん — bay coast; bayside area
• 湾内わんない — inside a bay
• 湾曲わんきょく — bending in; curved shape
• 湾口わんこう — bay mouth; entrance of a bay
• 湾入わんにゅう — inlet; small bay

The kanji 湾 combines the water radical 氵 with a phonetic element that hints at “bending” or “curving”. Together they capture the image of sea water curving inward along the land — a sheltered bay or inlet. From that idea we get words for bays, coastlines along a bay, and even 湾曲, something that bends gently like a shoreline.