T he synthetic-sounding call of a lone bird rises notably above a riot of birdsong. On the horizon, a purplish sunset is reflected in the vast waters of Europe’s largest wetland. “It’s like another world,” says Charlie Ottley, a British documentary maker who has presented two Netflix documentary series on Romania.

“It’s one of the most biodiverse places in the world, not just in Europe.” This moment on the top deck of the floating hotel my eight-year-old son Tommy and I are staying on marks the end of a long day in Romania’s Danube delta. This is where the Danube – which originates in Germany’s Black Forest and snakes through 10 countries – empties into the Black Sea.

“This is the Amazon of Europe,” Ottley says, gesturing to the sprawling maze of reed beds, canals, floating islands, marshes, lakes and forests. I have lived in Romania for nearly 10 years yet never explored the Danube delta. What I discover feels like a country within a country, a wilderness so unspoilt and expansive as to match or surpass the better-known Carpathian mountains for its rich wildlife and culture.

We’re part of a dozen-strong group on a tour of the wetland wilderness led by guide Daniel Petrescu, who has a deep knowledge of this Unesco-stamped nature reservation and a knack for imitating bird calls. Our open-deck viewing boat departs from Tulcea, the gateway city to the delta close to the Ukrainian border, and slowly moves through the Trofilca Canal, where 20 breeding p.