In depth
Container hubs and the Caribbean: where Mariel fits in global shipping
Container shipping works through hubs. A few very large ports exchange boxes between the biggest ships, and smaller feeder vessels carry them on to regional destinations. This guide explains how that system works, what a port like Mariel has to offer inside it, and what the competition looks like in the Caribbean, using the physical dimensions of ships and canals as a guide to what is possible.
How container hubs work
A container ship that crosses an ocean carries thousands of twenty-foot equivalent units, or TEU. Calling at every small port would be slow and expensive, so lines concentrate their big ships at a limited number of hub ports, where containers are unloaded and reloaded onto smaller feeder vessels that serve smaller ports. This process, known as transshipment, allows large ships to keep to a few efficient stops.
A good hub needs deep water, long quays, powerful cranes, a large yard, efficient customs and a position near the main sea lanes. It also needs a regulatory environment in which lines are comfortable operating, and a reputation for reliable productivity, measured as moves per hour. Hubs compete fiercely, and a line will change its call pattern for a small improvement in cost or time.
Ship sizes and the canal
The size of ships has been transformed by the Panama Canal. The original locks, in service from 1914, limited vessels to about 294 metres in length, 32 metres in beam and 12 metres of draft, a class called Panamax. A third set of locks, opened in 2016, allows ships of up to about 366 metres in length, 49 metres in beam and 15 metres of draft, known as neo-Panamax, which carry roughly two and a half to three times as many containers as the largest of the old class.
Ports that wish to serve these vessels need quays with depths above fifteen metres alongside and cranes that can reach across wide decks. Mariel was designed with the neo-Panamax in mind, and its quay depth places it among the deepest in the region. The question is whether lines choose to bring ships there.
The Caribbean competition
The Caribbean already has several established hubs. Kingston in Jamaica, Freeport in the Bahamas, Caucedo in the Dominican Republic and Colón in Panama all serve as transshipment ports for the region. Cartagena in Colombia and Port Everglades and Miami in Florida serve large markets directly. Each of these ports has its own advantages, such as a position on the east-west route, connections to a large consumer market, or a free-zone regime.
Mariel's advantages are its geography, close to the Straits of Florida and the Yucatán Channel, and its depth. Its disadvantages are the small size of the Cuban market, limited cargo for exports, the cost of being outside the networks of some carriers, and the effect of sanctions on shipping lines with US business. A hub needs volume, and volume depends on cargo, which is why developing it is a long-term task.
Cabotage and feeders
Feeder vessels, usually carrying between a few hundred and a few thousand containers, link a hub to nearby ports. In Cuba's case, feeders could carry containers from Mariel to ports in the Caribbean and Central America, and coastal shipping could distribute them to the island's own ports. The island's long shape makes coastal shipping attractive in principle, since moving cargo by sea between Mariel, Cienfuegos and Santiago might be cheaper than road haulage. In practice the volume and the age of the coastal fleet have limited this.
The sanctions variable
A line that calls at Cuba may face consequences in the United States. One US law restricts vessels that have loaded or unloaded goods in Cuba from loading or unloading in US ports for a period of 180 days, with exceptions. The result is that carriers with significant US business tend to avoid scheduled calls in Cuba, while carriers without it, or with dedicated vessels, can serve the island. Because the rules can be amended, the current position should be read directly from official US sources.
For a shipper, it means that the choice of carrier is narrower than it would be for a comparable market, which affects frequency and rates. This is one of the main reasons why a deep-water port by itself does not make a hub.
How to read claims about Mariel's future
Announcements about Mariel often cite capacity or potential. A useful test is to look for the volume actually handled, expressed in TEU for a named year, the list of lines with regular calls, and the productivity of the terminal. These data are published irregularly, so independent trade statistics and shipping databases give a better picture than promotional material.
This page explains the concepts and does not represent the port or any carrier. It does not sell shipping or transshipment services.
Measuring a terminal: the numbers behind productivity
Port professionals use a small set of measures to compare terminals. Berth productivity is the number of container moves per hour for a ship at the quay. Crane productivity is the number of moves per hour for each ship-to-shore crane. Dwell time is the average number of days a container stays in the yard before leaving. Yard density measures how many containers are stored per hectare, and vessel turnaround time counts the hours between arrival and departure.
A terminal that scores well on these measures is attractive to shipping lines because it saves time, and time is the largest cost for a large ship. A reader who sees claims about a port should ask which of these metrics are being reported, for which period, and by whom. Independent databases, such as those maintained by the World Bank and UNCTAD, publish port performance indexes for many countries.
Draft, tides and the physical limits of a quay
Ship draft is the depth of the hull below the waterline, and a port must have more water than the ship's draft. Caribbean tides are small, usually well under a metre, so the depth alongside a quay is nearly constant, unlike ports on large-tide coasts where ships wait for high water. For container ships, the draft depends on the load, and a fully laden neo-Panamax ship can draw around fifteen metres.
In addition to depth, a terminal needs space to turn ships, which is why a wide turning basin is a feature of well-designed harbours. Mooring systems, fenders and tugs must also be suited to the size of vessels. These details are rarely mentioned in news, but they are why some ports can receive large ships and others cannot.
Reefers, dangerous cargo and special handling
A container terminal handles more than standard boxes. Refrigerated containers need electrical sockets and monitoring. Dangerous goods, from chemicals to fuel, require segregation and documentation under the International Maritime Dangerous Goods Code. Oversize cargo such as machinery may need special lifting equipment. A terminal's ability to handle these categories affects the range of cargo it can attract.
Each special category also relies on trained staff, emergency procedures and links with local authorities. For a new terminal, building up this experience takes time, and shippers often test a new port with simple cargo before trusting it with high-value or sensitive consignments.
Container-shipping terms that are often confused
News about ports mixes several terms that mean different things. A TEU is one twenty-foot container, while an FEU is a forty-foot container, which counts as two TEU. A liner service is a scheduled route with fixed ports of call, like a bus line, while tramp shipping goes wherever a charterer sends the ship, like a taxi. Carriers often share ships in alliances, each selling space on the others' vessels, so one ship may carry boxes for several brands.
A slot is space for one container on a ship, and a slot charter lets one carrier buy slots on another's vessel. A reefer is a refrigerated container. A feeder is a small ship that moves boxes between a hub and nearby ports. Transshipment means changing ships at an intermediate port, while gateway cargo is cargo whose origin or destination is the country itself. The distinction matters for Mariel because transshipment depends on lines choosing it as a hub, while gateway cargo depends on Cuban trade.
When a report says a port handled a certain number of containers, it is worth asking whether the figure counts loaded boxes only or empties too, whether it is TEU or boxes, and whether it includes transshipment. Without that detail, two ports' figures cannot be compared.
Why transshipment needs trust
A transshipment hub holds other companies' cargo for days at a time, so the lines that use it must be confident that boxes will not be lost, delayed or seized. This depends on predictable customs rules, clear liability, reliable data exchange and a track record. Establishing trust takes years of consistent performance, and it can be lost quickly after an incident. This is one reason why newly built terminals with excellent engineering can still attract few lines at first.
How lines decide where to call
Container lines choose ports by comparing cost per box, including port charges, cranes, time in port and inland connections, against the revenue from cargo available. They also weigh the risk of delays, labour disputes and regulatory changes. A new terminal often needs a committed anchor customer, a line that guarantees volume, before others follow. This is why announcements of a partnership with a major line matter more than announcements of new cranes.
Common questions
- What does TEU mean?
- Twenty-foot equivalent unit, the standard measure of container capacity.
- What is a neo-Panamax ship?
- A vessel up to about 366 metres long, 49 metres wide and 15 metres of draft that can use the Panama Canal's third locks, opened in 2016.
- Which ports compete with Mariel?
- Kingston, Freeport, Caucedo, Colón and Cartagena, among others.
- How do US rules affect shipping lines?
- A 180-day restriction applies to vessels that trade with Cuba and then call at US ports, subject to exceptions. Read the current rules on official US sources.
- Do you sell shipping?
- No. This page is information only.
- What is a gantry crane?
- A large crane that moves containers between ship and quay, running on rails along the berth. Their reach and number determine how large a vessel a terminal can serve and how quickly.
- How long does a big ship stay in port?
- Typically a day or two for a large container ship, depending on the number of containers to move and the terminal's productivity. Shorter stays are more attractive to lines.
Official sources and where to go next
Links open the publisher's own site. CubaAtlas does not operate, sell, book or clear anything and earns nothing from these links.