The Yellow Sea: A Semi-Enclosed Marginal Sea Without a Single "Length"

The Yellow Sea (Huang Hai / Hwanghae) is a marginal sea of the Western Pacific, semi-enclosed by China, North Korea, and South Korea. Unlike a river or linear strait, it has no single defined "length"—its dimensions depend entirely on how boundaries are drawn.

Geographic Extent (Approximate)

North-South extent: ~600 km (370 mi) — from Liaodong Peninsula (China) to Jeju Strait (Korea).
East-West extent: ~700 km (435 mi) — from Korean Peninsula to Jiangsu/Shandong coast (China).
Surface area: ~380,000 km² (147,000 sq mi).
Average depth: 44 m (144 ft) — very shallow for a sea.
Max depth: 106 m (348 ft) — in the northern Yellow Sea trough.

Why "Length" Is the Wrong Metric

The Yellow Sea is a **broad, shallow basin** on the continental shelf, not a channel. Its boundaries are transitional:
• North: Bohai Sea (separated by arbitrary line between Liaodong and Shandong peninsulas).
• East: Korean Peninsula coast.
• South: Jeju Strait / East China Sea (no sharp boundary).
• West: Chinese mainland coast.

Any "length" measurement would be an arbitrary chord across an irregular shape—geographically meaningless.

Significance Despite Shallow Depth

Productivity: Nutrient-rich runoff (Yellow River, Yangtze, Han River) + shallow depth + tidal mixing = high primary production. Major fisheries (anchovy, croaker, crab, clams).
Strategic: Access to Beijing (via Bohai), Seoul (Incheon), major Chinese ports (Qingdao, Dalian, Tianjin).
Environmental stress: Heavy pollution, habitat loss (tidal flats reclaimed), overfishing, algal blooms (green tides).
Geopolitics: Disputed maritime boundaries (North/South Korea, China/Korea).