The town was titled "Great Grimsby" to distinguish it from Little Grimsby, a village about 14 miles (22 km) to the south, near Louth.
The town had a population of 88,243 in 2011. It is physically linked to and forms a conurbation with the adjoining town of Cleethorpes. Some 11,000 of its residents live in the village of Scartho, which was absorbed into Grimsby before 20th-century laws on the green belt were passed. All three areas come under the jurisdiction of the same unitary authority, North East Lincolnshire. It is close to the main terminus of the A180, which ends in Cleethorpes.
Grimsby lies in the national character areas of the Humber, and the Lincolnshire coast and Marshes; it is predominantly low in topography. The town was historically settled on low-lying islands and raised areas of the Humber marsh, and subsequently expanded onto the surrounding marshes as they were drained. The town still has areas named East Marsh and West Marsh. The Lincolnshire Wolds are situated to the south west of the town, from which the town's River Freshney rises.
Grimsby is strongly linked with the sea fishing industry, which once generated wealth for the town. At its peak in the 1950s, it was the largest and busiest fishing port in the world. As a result of the Cod Wars with Iceland, this industry has been in decline for many years. In 1970 around 400 trawlers were based in the port, by 2013 only 5 trawlers remain based there. By comparison, 15 vessels are used to maintain offshore wind farms in the North Sea. The town still has the largest fish market in the UK, but most of what is sold is now brought overland from other ports or Iceland via containerisation. Of the 18,000 tonnes of fresh fish sold in Grimsby fish market in 2012, almost 13,000 tonnes, mainly cod and haddock, came from Iceland.
Today, Greater Grimsby is home to around 500 food-related companies, giving it one of the largest concentrations of food manufacturing, research, storage, and distribution in Europe. The local council has promoted the city as Europe's Food Town for nearly twenty years. In 1999, the BBC reported that more pizzas were produced in the town than anywhere else in Europe, including Italy.
Grimsby is recognised as the main centre of the UK fish-processing industry; 70% of the UK's fish processing industry is located there.In recent years, this expertise has led to diversification into all forms of frozen and chilled foods. The town is one of the largest centres of fish processing in Europe. More than 100 local companies are involved in fresh and frozen fish production, the largest of which is the Findus Group (see Lion Capital LLP), comprising Young's Seafood and Findus. Its corporate headquarters are in the town. Young's is a major employer in the area, with some 2,500 people based at its headquarters. From this base, Young’s has a global sourcing operation supplying 60 species from 30 countries.
Traditional Grimsby smoked fish has been awarded a Protected Geographical Indication (PGI) in 2009 by the European Union. The traditional process uses overnight cold smoking using sawdust in tall chimneys, roughly 1 by 2 metres (3 ft 3 in by 6 ft 7 in) square and 10m high.
Other major seafood companies include the Icelandic-owned Coldwater Seafood, employing more than 700 people across its sites in Grimsby; and Five Star Fish, a supplier of fish products to the UK foodservice market.
The £5.6 million Humber Seafood Institute, the first of its kind in the UK, opened in 2008. Backed by Yorkshire Forward, North East Lincolnshire Council, and the European Regional Development Fund, the HSI is managed by the local council. Tenants include the Seafish Industry Authority and Grimsby Institute and University Centre. Greater Grimsby is a European centre of excellence in the production of chilled prepared meals, and the area has the largest concentration of cold-storage facilities in Europe.
The Port of Grimsby has been in use since the medieval period. The first enclosed dock, later known as the Old Dock, was built in the 1790s by the Grimsby Haven Company. Major expansion came with the coming of the railways, and construction of the Royal Dock, Grimsby in the 1840s. A Fish Dock was added in 1857, and the fish docks expanded over the next 80 years, with Grimsby becoming a major fishing centre. The Old dock was expanded to form Alexandra Dock in the 1880s.
Fishing activities were reduced to a fraction of former levels in the second half of the twentieth century. The current port is a centre for car import (and export). Since 1975, it handles general cargo. In the early 21st century, it has developed as a wind farm maintenance base.