The big idea: Borders don't stop at the coast. Maritime borders divide the sea.
Why the sea is contested
- Control of the sea means control of fish, oil, gas, shipping lanes and strategic position.
- Because the sea is vast and valuable, maritime borders are increasingly contested.
- They are governed loosely by the UNCLOS treaty.
- Resources — an EEZ can hold huge stocks of fish, oil and gas worth billions.
- Trade — most world trade goes by sea, so control of shipping lanes is strategic power.
- Overlapping claims — where coasts are close, states' 200-mile zones overlap and must be divided.
- Islands — owning a tiny island can extend a state's maritime zone over a vast area, so islands are fiercely claimed.
The sea is the new frontier of border disputes: As land borders settled and sea resources grew more valuable and reachable, maritime borders became a rising source of tension. UNCLOS sets the rules, but not every powerful state fully accepts them, and disputes over islands and overlapping EEZs mix law, resources and raw power — making the sea a key global political challenge.
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Maritime disputes are hard because the stakes are huge (resources + strategy), the law (UNCLOS) is not always enforced, and owning a small island can unlock a vast EEZ — so states claim aggressively.
Why islands cause outsized disputes
Under UNCLOS, an island can generate its own territorial waters and EEZ, so control of a tiny, uninhabited rock can extend a state's rights over hundreds of miles of resource-rich sea. This is why states fiercely claim, occupy and even build up small islands and reefs — the prize is the sea around them.
Why UNCLOS is not enough
UNCLOS provides the rules and a tribunal, but it cannot compel a powerful state that rejects a ruling, and some major states have not fully accepted it — so maritime borders are governed by law that is real but weakly enforced, leaving disputes to be settled by negotiation, pressure or force.
Case study — an overlapping-claims sea dispute: A classic maritime challenge arises where several states border a resource-rich sea and their EEZ claims overlap, often around disputed islands.
One state
- Cites UNCLOS and a tribunal ruling
Another state
- Cites history
- Or occupies the islands and rejects the ruling
Why the dispute persists
- It mixes fish, oil, gas, shipping lanes and national pride.
- The sea is hard to police, and the law is hard to enforce.
- So it can persist for years, with periodic tension.
The HL lesson: Maritime borders are where international law, resources and power collide. Legal rulings only settle a dispute if the powerful choose to accept them.
The key point: Maritime borders divide the valuable sea into zones (territorial waters, EEZ, high seas) under UNCLOS, but disputes arise over overlapping claims and islands because the sea holds huge resources and strategic power. Legal rules exist but are weakly enforced, so maritime borders mix law, resources and power.
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Should maritime disputes be settled by law (UNCLOS rulings) or by power and negotiation? And how should the world respond when a state ignores a ruling? Weigh it — and be ready to recommend.
The case for joint development
Where a clean border is impossible, states can agree to jointly develop and share the resources of a disputed sea, setting the sovereignty question aside — turning a zero-sum fight into a shared gain, though it requires enough trust to strike the deal.
Why enforcement is the weak link
A tribunal can rule, but there is no maritime police to make a powerful state comply, so a ruling only settles a dispute if backed by pressure, alliances and the disputing states' willingness to accept it — which is exactly what is often missing.
Two perspectives — weigh them: One view: maritime disputes should be settled by UNCLOS and impartial law, which protects weaker states. Another view: without enforcement, power decides, and strong states ignore rulings. Strong HL answers judge that upholding UNCLOS and rulings is the fairest route and should be backed by collective pressure, while joint development offers a pragmatic path where a clean border is impossible.
How maritime borders come up in Paper 3: Paper 3 stimulus might show a sea dispute, an UNCLOS ruling, or an island being claimed.
What to do with the stimulus
Analyse
Analyse the mix of law, resources and power.
Recommend
Recommend a response — usually upholding law + collective pressure + joint development.
Go beyond description
Don't just describe the dispute.
How Paper 3 rewards you (HL)
Understand
Show you understand the challenge and the stimulus material accurately.
base
Analyse
Break the challenge down — causes, actors, perspectives — using the material.
analyse
Recommend
Propose and justify a course of action — the Paper-3-specific skill.
recommend
Synthesise
Pull the material together into a judged, evaluated response.
top
Recommend how states should resolve a maritime border dispute over a resource-rich sea.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Common mistakes (Paper 3): 1. Ignoring UNCLOS and the zones. Use the legal framework.
2. Forgetting islands extend the EEZ. That's why they're fought over.
3. Assuming a ruling settles it. Enforcement is the weak link.
4. Only describing. Analyse + recommend.
5. Missing joint development. It's a key pragmatic option.