Maritime routing
Realistic sea routing for Panamax, VLCC, and ULCV vessels, reflecting global chokepoints, canal limits, and fallback cape routes for accurate distance calculations.
Maritime routing is one of the cornerstones of international trade. More than 80% of global goods are transported by sea, and understanding how vessels move across the oceans is critical for logistics, planning, and distance calculations.
Unlike roads or airways, sea routes are not unlimited open space: large vessels must navigate through specific passages, straits, and canals that connect oceans and seas. These chokepoints can become bottlenecks due to draft limits, geopolitical risks, congestion, or seasonal ice.
Distance Tools models these maritime passages in order to provide realistic distance calculations for different vessel classes. This ensures that when you compute a route for a container ship or an oil tanker, the distances reflect the actual navigable routes these vessels use in practice.
By modeling real-world maritime constraints, Distance Tools can:
Produce realistic sea distances for container and tanker routes.
Adapt to closures and risks (e.g. Suez blocked, Panama drought).
Support multiple vessel profiles for flexible planning.
Reflect both global arteries (Suez, Panama, Malacca) and fallback routes (Capes, Lombok, Makassar).
This ensures that when you request maritime distances via the Distance API, the numbers reflect how ships actually sail, not just straight-line great-circle distances.
Vessel classes
Different vessels have different constraints. A small Panamax ship can transit most man-made canals, while the largest oil tankers (VLCC) or container ships (ULCV) are too deep or wide for some passages.
Distance Tools currently models three major vessel classes:
Panamax → smaller bulk carriers and container ships designed to fit the original Panama Canal.
VLCC (Very Large Crude Carrier) → huge oil tankers, some of the deepest draft vessels in the world.
ULCV (Ultra Large Container Vessel) → the largest container ships used on Asia–Europe trade lanes.
Vessel restrictions
≤80k DWT, ~12m draft
Kiel Canal (draft-limited), Magellan Strait (difficult weather), Torres Strait (shallow)
Bering Strait, Northwest Passage, Northeast Passage, Corinth Canal
VLCC
200–320k DWT, ~20–22m draft
Malacca Strait (Malaccamax limit), Magellan Strait (navigable but impractical)
Suez Canal (too deep fully laden), Panama Canal, Sunda Strait, Kiel Canal, Corinth Canal, Bosphorus & Dardanelles (too narrow), Torres Strait, Arctic routes (NW/NE/Bering)
ULCV
14–24k TEU, ~14–16m draft
Malacca Strait (draft/size limit), Panama Canal (≤14k TEU only), Magellan Strait (navigable but impractical)
Sunda Strait, Kiel Canal, Corinth Canal, Bosphorus & Dardanelles, Torres Strait, Arctic routes (NW/NE/Bering)
Routing profiles
The table below summarizes the major global chokepoints and whether each vessel class can use them.
Suez Canal
✅ Allowed
❌ Forbidden
✅ Allowed
Core Asia–Europe artery; VLCC must lighter
Panama Canal
✅ Allowed (old locks)
❌ Forbidden
⚠️ Restricted (≤14k TEU, Neopanamax)
Drought can restrict further
Malacca Strait
✅ Allowed
⚠️ Restricted (Malaccamax ~200k DWT)
⚠️ Restricted (ULCV near draft limits)
Heavy congestion
Sunda Strait
✅ Allowed (regional)
❌ Forbidden
❌ Forbidden
Too shallow/narrow for VLCC/ULCV
Gibraltar Strait
✅ Allowed
✅ Allowed
✅ Allowed
Deep water, universal
Bering Strait
❌ Forbidden
❌ Forbidden
❌ Forbidden
Arctic only, no commerce
Magellan Strait
⚠️ Restricted
⚠️ Restricted
⚠️ Restricted
Navigable but impractical; Cape Horn preferred
Bab el-Mandeb Strait
✅ Allowed
✅ Allowed
✅ Allowed
Strategic; conflict/piracy risks
Kiel Canal
⚠️ Restricted (draft-limited)
❌ Forbidden
❌ Forbidden
Max draft ~9.5m
Corinth Canal
❌ Forbidden
❌ Forbidden
❌ Forbidden
Very small ships only
Northwest Passage
❌ Forbidden
❌ Forbidden
❌ Forbidden
Not commercially viable
Northeast Passage
❌ Forbidden
❌ Forbidden
❌ Forbidden
Not commercially viable
Bosphorus Strait
✅ Allowed (small Panamax)
❌ Forbidden
❌ Forbidden
Narrow, pilotage; Black Sea access only
Dardanelles Strait
✅ Allowed (small Panamax)
❌ Forbidden
❌ Forbidden
Companion to Bosphorus
Strait of Hormuz
✅ Allowed
✅ Allowed
✅ Allowed
Vital for oil, geopolitical risk
Lombok Strait
✅ Allowed
✅ Allowed
✅ Allowed
Deep alternative to Malacca
Makassar Strait
✅ Allowed
✅ Allowed
✅ Allowed
Used with Lombok for bypass
Torres Strait
⚠️ Restricted (draft-limited)
❌ Forbidden
❌ Forbidden
Very shallow, regional trades
Cape of Good Hope
✅ Allowed
✅ Allowed
✅ Allowed
Fallback route for Suez closures
Cape Horn
✅ Allowed
✅ Allowed
✅ Allowed
Harsh conditions, fallback for Panama oversize
When using the default profile, Distance Tools applies no restrictions — all passages are treated as open, regardless of vessel size.
Open-Source Routing Engine
Maritime routing in Distance Tools is powered by the open-source library searoutes. This library builds realistic sea networks from authoritative datasets and applies the vessel class restrictions shown above. By relying on open data and open technology, we ensure transparency in how routes are calculated and give developers confidence in both the methods and results.
Last updated