Once again, Steven Spielberg ruined my morning swim.

Conditions should have been ideal. I was chest-deep in a lake known locally as the Sweet Sea, sand squelching between my toes, the water as warm as a paddling pool in summer and as silvery-flat as a drinks tray.

A chorus of crickets was serenading me from the shore. Dragonflies hovered in front of my nose like tiny Chinooks. Skinny white egrets waded nearby, looking for fishy breakfasts. On the shore behind me, a perfect cone-shaped volcano rose up, its peak hidden in a curly wig of white cloud. This was why I’d come to Nicaragua and Isla de Ometepe. And yet...

“You might see a bull shark if you’re lucky,” I’d been told. “There aren’t as many as there used to be, but they’re the only freshwater ones in the world.”

I started to swim and pulled up almost immediately. It was no good. The dreadful paranoias Spielberg had unleashed with his damn shark film were too much. I was in water where you couldn’t see your feet. It was dawn. To swim, it was quite obvious, would be to invite certain death. I sighed and made for the beach. Rapidly.

By comparison, the volcano seemed almost benign. Ometepe has two - Volcan Maderas at its southern tip, and to the north, Volcan Concepcion, glaring out over the enormous Lago de Nicaragua like a smoking sentry. Seen from the lake, it looks like the classic secret lair of a James Bond villain. You half expect it to split open in front of your eyes and launch an escape pod into orbit.

In climbing Concepcion the day before, I had sweated my T-shirt into an early grave. Among the lemon groves and eucalyptus trees on the lower slopes, it had been like trekking through a kiln. Towards the top - where the lush vegetation gave way to loose volcanic rocks and angular black boulders blasted down the slopes during the last eruption - it was like walking up hell’s garden path.

Still - what a volcano takes, it gives back. Salvation came in the hot springs at its base. At Ojo de Agua, I let the aches ease away in warm, green waters under a canopy of silk-cotton trees and sun-bleached oaks, and watched yellow butterflies fly frantic sorties overhead.

There’s also the dinner-time bounty. In Concepcion’s rich, fertile, dangerous soils grow the tastiest plantains, avocados and watermelons in Central America. Ometepe is one big natural experiment in organic farming.

“We’re very proud of our island,” a local tells me after serving up grilled guapote fish, fresh from the lake.

“You know they are making a new long list for the seven natural wonders of the world?” he says. “Ometepe is 74th.”

You can only assume the judges simply haven’t bothered visiting. Maybe they, like many other people, still automatically associate Nicaragua with the brutal cold-war conflict that gave us the Contras, arms-for-hostages and Colonel Oliver North, even though the country has been at peace for 20 years.

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