Kunta Kinteh Island, The Gambia: The island where a whole, terrifying history is about to be lost

The river is eating up the island of Kunta Kinteh. Its tide is ravishing the fragile banks so that each year this speck of land in the middle of the Gambia River is reduced to a smaller version of its previous self. So diminished is it, the river will soon swallow its remains, taking ruins and baobabs and people's stories with it. A whole, terrifying history will be lost.

We're upriver from The Gambia's capital, Banjul, itself an island lodged like a stone in the river mouth. Ours is a peaceful visitation, unlike those early European incursions long this waterway – first the Germans looking to establish an empire in West Africa, then Portuguese, Dutch, French and British slavers on the hunt for quarry.

They found their human cargo here, in villages up and down the riverbanks and spread out on the flats inland. They were taken in boats to Fort James – as this islet was named by the British – and held in a slave house before being shipped to the Americas. Kunta Kinteh – the Mandinka man immortalised in Alex Haley's book (and, later, the television miniseries) Roots – was held here, within view of the village where he was born. The island was renamed for him in 2011.

"Each time a ship docked here, around 100 slaves were taken," says guide Lamin Njie. He weaves through the island's scattered ruins, somehow making sense of them. Here was the landing place where slaves were sorted, separated and branded. There was the cultural room where their names were changed.

"[The slavers] wanted them to forget their family names and their culture," says Njie. "That's why they changed their names to Clara, Sarah, Nancy, William, Fanny, Abraham, Jackson. That's why [American human rights activist] Malcolm didn't want a second name. He called himself [Malcolm] X."

But Kunta Kinteh refused to answer to his new name, Toby, and suffered brutal consequences. Even when Britain abolished slavery in 1833, slavers had the last word: the 90 people interred on this island at the time were told to swim to freedom on the opposite bank. They all drowned.

The river seems to be listening to Njie's tragic stories, for it's angry today, chopping and spitting as we take a pirogue back to our yacht, the M/Y Harmony G. The islet recedes into the distance until it's nothing but a baobab planted in water. Though a UNESCO World Heritage site, it appears to be as much a victim of the river as its prisoners were of the slave trade.

The story takes a happy turn upstream, where an unnamed island speaks to belonging instead of incarceration: no one is allowed onshore except for the ranger who comes each day to feed and rehabilitate the rescued chimps now roaming free in this forested realm.