A bulk carrier or bulker is a merchant ship specially designed to transport unpackaged bulk cargo—such as grain, coal, ore, steel coils, and cement—in its cargo holds. Since the first specialized bulk carrier was built in 1852, economic forces have led to increased size and sophistication of these ships. Today's bulk carriers are specially designed to maximize capacity, safety, efficiency, and durability.

Today, bulk carriers make up 21 percent of the world's merchant fleets, and they range in size from single-hold mini-bulk carriers to mammoth ore ships able to carry 400,000 metric tons of deadweight (DWT). A number of specialized designs exist: some can unload their own cargo, some depend on port facilities for unloading, and some even package the cargo as it is loaded. Over half of all bulk carriers have Greek, Japanese, or Chinese owners, and more than a quarter are registered in Panama. South Korea is the largest single builder of bulk carriers, and 82 percent of these ships were built in Asia.

On bulk carriers, crews are involved in operation, management, and maintenance of the vessel, taking care of safety, navigation, maintenance, and cargo care, in accordance with international maritime legislation. Crews can range in size from three people on the smallest ships to over 30 on the largest.

Cargo loading operations vary in complexity, and loading and discharging of cargo can take several days. Bulk carriers can be gearless (dependent upon terminal equipment) or geared (having cranes integral to the vessel).

Bulk cargo can be very dense, corrosive, or abrasive. This can present safety problems that can threaten a ship: problems such as cargo shifting, spontaneous combustion, and cargo saturation. The use of old ships that have corrosion problems—as well as the bulk carriers' large hatchways—have been linked to a spate of bulk carrier sinkings in the 1990s. These large hatchways, important for efficient cargo handling, can allow the entry of large volumes of water in storms and accelerate sinking once a vessel has listed or heeled. New international regulations have since been introduced to improve ship design and inspection and to streamline the process for crews to abandon ship.

Bulk carriers are segregated into six major size categories: small, handysize, handymax, panamax, capesize, and very large. Very large bulk and ore carriers fall into the capesize category but are often considered separately.

Categories occur in regional trade, such as Kamsarmax, Seawaymax, Setouchmax, Dunkirkmax, and Newcastlemax also appear in regional trade.

• "Kamsarmax": Maximum length overall 229 meters refers to a new type of ship, larger than panamax, that is suitable for berthing at the Port of Kamsar (Republic of Guinea), where the major loading terminal of bauxite is restricted to vessels not more than 229 meters.

• "Newcastlemax": Maximum beam 50 meters, and maximum length overall of 300 meters Refers to the largest vessel able to enter the port of Newcastle, Australia at about 185,000 DWT

• "Setouchmax": About 203,000 DWT, being the largest vessels able to navigate the Setouchi Sea, Japan

• "Seawaymax": LOA 226 m max / 7.92 m draft. Refers to the largest vessel that can pass through the canal locks of the St. Lawrence Seaway (Great Lakes, Canada)

• "Malaccamax": LOA 330 m / 20 m draft / 300,000 DWT, Refers to the largest vessel that can pass through the Straits of Malacca.

• "Dunkirkmax": Maximum allowable beam = 45 m / LOA 289 m. max (175,000 DWT approx) for the eastern harbour lock in the Port of Dunkirk (France)

Mini-bulk carriers are prevalent in the category of small vessels with a capacity of under 10,000 DWT. Mini-bulk carriers carry from 500 to 2,500 tons, have a single hold, and are designed for river transport. They are often built to be able to pass under bridges and have small crews of three to eight people.

Handysize and Handymax ships are general purpose in nature.These two segments represent 71% of all bulk carriers over 10,000 DWT and also have the highest rate of growth.This is partly due to new regulations coming into effect which put greater constraints on the building of larger vessels. Handymax ships are typically 150–200 m in length and 52,000 – 58,000 DWT with five cargo holds and four cranes.^[4] These ships are also general purpose in nature.

The size of a Panamax vessel is limited by the Panama canal's lock chambers, which can accommodate ships with a beam of up to 32.31 m, a length overall of up to 294.13 m, and a draft of up to 12.04 m.

Capesize ships are too large to traverse the Panama canal and must round Cape Horn to travel between the Pacific and Atlantic oceans. Earlier, Capesize ships could not traverse the Suez and needed to go around the Cape of Good Hope. Recent deepening of the Suez canal to 66 ft (20 m) permits most Capesize ships to pass through it.

Capesize bulk carriers are specialized: 93% of their cargo is iron ore and coal.Some ships on the Great Lakes Waterway exceed Panamax dimensions but they are limited to use on the Great Lakes as they cannot pass through the smaller St. Lawrence Seaway to the ocean. Very large ore carriers and very large bulk carriers are a subset of the capesize category reserved for vessels over 200,000 DWT.Carriers of this size are almost always designed to carry iron ore.

In October 2022, Mitsui O.S.K. Lines (MOL)'s bulk carrier Shofu Maru arrived in Newcastle on its maiden voyage, becoming the first bulk carrier to be partially powered by hard sail wind power propulsion technology. A five percent fuel savings was anticipated.

General Bulk Carrier Types

Illustration	Description
	Geared bulk carriers are typically in the handysize to handymax size range although there are a small number of geared panamax vessels, like all bulk carriers they feature a series of holds covered by prominent hatch covers. They have cranes, derricks or conveyors that allow them to load or discharge cargo in ports without shore-based equipment. This gives geared bulk carriers flexibility in the cargoes they can carry and the routes they can travel. (Photo: A typical geared handysize bulk carrier.)
	Combined carriers are designed to transport both liquid and dry bulk cargoes. If both are carried simultaneously, they are segregated in separate holds and tanks. Combined carriers require special design and are expensive. They were prevalent in the 1970s, but their numbers have dwindled since 1990. (Photo: The oil pipeline and dry bulk hold aboard Maya.)
	Gearless carriers are bulk carriers without cranes or conveyors. These ships depend on shore-based equipment at their ports of call for loading and discharging. They range across all sizes, the larger bulk carriers (VLOCs) can only dock at the largest ports, some of these are designed with a single port-to-port trade in mind. The use of gearless bulk carriers avoids the costs of installing, operating, and maintaining cranes. (Photo: Berge Athen, a 225,000 ton gearless bulk carrier.)
	Self-dischargers are bulk carriers with conveyor belts, or with the use of an excavator that is fitted on a traverse running over the vessel's entire hatch, and that is able to move sideways as well. This allows them to discharge their cargo quickly and efficiently. (Photo: John B. Aird a self-discharging lake freighter.)
	Lakers are the bulk carriers prominent on the Great Lakes, often identifiable by having a forward house that helps in transiting locks. Operating in fresh water, these ships suffer much less corrosion damage and have a much longer lifespan than saltwater ships. As of 2005, there were 98 lakers of 10,000 DWT or over.(Photo: Edward L. Ryerson, a Great Lakes bulk carrier.)
	BIBO or "Bulk In, Bags Out" bulk carriers are equipped to bag cargo as it is unloaded. CHL Innovator, shown in the photo, is a BIBO bulk carrier. In one hour, this ship can unload 300 tons of bulk sugar and package it into 50 kg sacks