None of us can swim - not me, not my friends Chioma and Chinwe, not my brother Okey - and as we put on lifejackets at the Lagos boat club, I wonder why this is so. There was a swimming pool on the Nsukka campus of the University of Nigeria where we all grew up but my parents thought it dangerous - especially after a boy dived and died, his head hitting the bottom. Every year I resolve to learn how to swim. And every time I am on a boat, I perform the role of the terrified non-swimmer. I do it today. I am alarmed when the boat stalls after dirt is caught in the propeller.

The only swimmer is my friend Michiel, Dutch resident of Lagos, who lounges without a lifejacket, and who, when we speed bumpily past a “caution” sign, over the violent tides from the South Atlantic, points out that the Eko marina bridge above might collapse soon. A dense garbage of cans and plastic bags float past. Then they are washed away and for some minutes we see frothy water free of debris: a clean mirage. We speed past toilets that are thatch shacks raised on stilts. We speed past a huge boat, so sleek and psychedelic that it looks like a spacecraft. Wealthy Nigerian men like big boats, no matter how incongruous. We speed past Apapa, the shipping port, where shipping agents and ports authority squabble, and containers pile up, and lorries wait in frustrated queues.

We are going to a beach house in an unfamiliar verdant Lagos. Lagos is, for me, about a certain kind of unreasonable urban urgency, of traffic, people, humidity, energy, creativity, the roar of generators; and so to arrive at that beach house after 20 minutes on a boat, to step on a wide expanse of topaz-coloured sand, is to inhabit a stillness so calming that it makes me suspicious. I lie in the shade and read NEXT, a new Nigerian newspaper. Here, finally, is a newspaper that is keen to do the kind of interrogating journalism that a number of papers did before they were cowed by the military governments.

We eat watermelon and tasteless chicken. We talk about the secrecy surrounding our President's health. We talk about the Central Bank governor who is being attacked for saying the international financial crisis would not affect Nigeria even though corporations are already cutting jobs and a bank is already paying half-salaries.

The cooler evening breeze has arrived as we pack up to leave. The village children, for whom this is ordinary life and not a day on the beach, gather to see us off. They expect some money, and are charming and knowing when we give it to them. I wonder what they really think about us.

The next day, my publisher Muhtar and I meet to talk about the Farafina Trust, which we have set up to raise money to run literary programmes. We are worried that the Nigerian stock market losses , the general sour mood, will mean less support. But the next day, a company signs on to sponsor our September creative writing workshop. We are elated.

I am reluctant to leave Lagos but I am on a plane to Baltimore two days later. I have been away from the United States, my second home, for seven months and perhaps it is in my imagination but I don't feel the usual tensing of my stomach at immigration. This is a new country. Barack Obama is President. I am struck by how shiny everything seems. I am struck by the power of this country: despite its problems, the world still buys its treasury bills. Television news is relentlessly insular; you would think that all that was happening in the world was that AIG paid bonuses to some men. I am pleased to be back. I have missed eating plums.

Chimamanda Ngozi Adichie talks at the Southbank Centre, London SE1 (0871 6632500), Friday, 7.30pm. The Thing Around Your Neck is published by Fourth Estate on April 2, £14.99

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