Exclusive Economic Zone & Maritime Boundary Simulator

Strait Geometry

Distance between coasts 300 km

Coastal irregularity 40%

Legal Layers

Show extended continental shelf (200–350 nmi) Highlight equidistance / median line

Live Readouts

Strait width

300 km · 162 nmi

Zone overlap requiring delimitation

0 nmi

State A maritime area

0 thousand km²

Legend

State A — territorial sea (12 nmi) State A — contiguous zone (24 nmi) State A — EEZ (200 nmi) State B — territorial / contiguous / EEZ State B shades Continental shelf claim (unopposed) High seas (beyond 200 nmi of both) Median line (Art. 15 equidistance) Land

How it works

UNCLOS measures every maritime zone as a distance from the baseline — the low-water line along the coast (here, two wavy coastlines facing each other across a strait):

Territorial sea:    d ≤ 12 nmi   (Art. 3)
Contiguous zone:    d ≤ 24 nmi   (Art. 33)
Exclusive Econ Zone: d ≤ 200 nmi  (Art. 57)
Extended shelf:      d ≤ 350 nmi  (Art. 76, simplified flat limit)

1 nautical mile (nmi) = 1.852 km. For every point of sea the simulator finds the shortest distance to the nearest point on each state's baseline (d_A, d_B) and colors it by whichever coast is closer, up to that state's 200 nmi limit.

When two coasts are less than 400 nmi apart, their 200 nmi claims overlap. UNCLOS Article 15 sets the default boundary as the equidistance / median line — the set of points equidistant from the two baselines (d_A = d_B) — unless historic title or special circumstances justify another line. That's the bright line the "median line" toggle traces here.

Beyond 200 nmi, a coastal state can still claim the seabed (not the water column) as extended continental shelf out to 350 nmi if no other state's EEZ already reaches there — shown as the hatched-look band when the toggle is on.

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