Atlantic Worlds: National Maritime Museum, London

"By navigation, the whole world is connected and the most distant parts of it correspond with each other," wrote John Entick in his volume A New Naval History (1757).

It would have been more accurate to say that by slavery and navigation, the world corresponds, which was to remain the case in the British empire long after the transatlantic slave trade was made illegal.

In keeping with last year's commemoration of the 200th anniversary of the abolition of the transatlantic slave trade act, the National Maritime Museum now gives greater prominence to the brutality involved in the trade.

Atlantic Worlds, the maritime museum's new permanent gallery, fills a long space formerly devoted to seaborne trade across the British empire.

Global colonialism and conquest has given way to four less overtly flag-waving themes: exploration and cultural encounters; trade and commerce; enslavement and resistance; and war and conflict. As its new title suggests, the focus has narrowed (a gallery about the Indian and Pacific Oceans is next in line).

The wheel of traded goods (other than humans) provides an eye-catching start - sugar, coffee, tobacco, cotton, fish and metals. Each is shown in its most basic form, then again as the products that were sold around the globe.

Objects drawn from the collection are a strong point. There are tiny brass weights in the shape of cannons - made in Akan, Ghana, for measuring gold dust - and a 16th-century Spanish astrolabe used to tell time by using the sun or stars.

A set piece about coffee-houses is particularly evocative, and features a stunning embroidered waistcoat panel dating from 1786. At the beginning of the 18th century the English drank about 10 times as much coffee than they did tea, both sweetened by sugar.

The imports gave rise to the coffee-house craze. In their heyday, there were about 2,000 in London, the places to strike deals or spread ideas, even unthinkable ones, such as freeing the slaves.

Navigation can be a problem in this gallery. It is not clear whether the visitor is meant to move along one side of the gallery and up the other or list from side to side. One moment I am eyeballing the three giants of Elizabethan exploration, the next I am trying to comprehend from a ship's model just how cramped a voyage to the new world might have been.

This is because the gallery can be entered from either end - which makes the thematic arrangement sensible, but doesn't overcome the sense that the stories should be told chronologically.

A small gallery space with a display of 18th-century prints offers opportunities for changing displays. The current crop shows satirical work by the likes of Hogarth, mocking the rich and famous - such as Admiral Lord Nelson with Emma Hamilton - for smoking tobacco, which was frowned upon in some quarters in the 18th century, while its production by enslaved labour and its sale was a major source of revenue for the British economy.

At the heart of the gallery is Africa and enslaved Africans. By the 1730s, Britain had become the largest slave trading country in the world - 3.4 million enslaved Africans were transported in British ships - and powerful objects from the museum's collection are on show.

To its credit, the museum does not whitewash this aspect of British history, nor does it try to shift the blame. We see Sir John Hawkins, who transported 1,200 slaves to the Caribbean, all confident and bejewelled.

Hawkins was the first English slave trader; on his first voyage he described capturing 300 Africans "by the sword and partly by other means". In the Caribbean he sold them to the Spanish for "hides, ginger, sugars, and some quantity of pearls". On his last slaving voyage he was accompanied by the young Francis Drake.

Even more powerful are the shackles, leg irons and a blunderbuss on show. Arranged simply in cases and spotlit, curiously few visitors paused to engage with these objects.

The stories of those who resisted and campaigned for the abolition of transatlantic slavery are represented by a series of tokens, medallions and halfpennies. Prints of prominent figures such as Olaudah Equiano, William Wilberforce and John Newton - himself a renowned slave ship captain, later a prominent abolitionist and composer of Amazing Grace - are displayed on a nifty fold-out unit rather like a poster rack.

There is also an anti-slavery woolwork picture dating from around 1820 - a kneeling African - an iconic image that was originally a design for Wedgwood ceramics (though none are on show here). The image is repeated on a silk pincushion of 1827.

On the reverse, apparently, is an extract from the Royal Jamaican Gazette with a notice of the sale of a child - a small mirror would have reflected this for visitors.

The gallery ends (or begins, depending on which way you come in) with a look at events such as the Seven Years' War (1756-1763), fought between Britain and France and resulting in Britain controlling large tracts of North America and the Caribbean.

In a sense it is typical of the whole gallery, where there are so many stories being told. And the end result, you fear, is that nothing truly stands out and stops the visitor in their tracks.

Caroline Worthington is the director of the Florence Nightingale Museum, London