“Whale Wars” star Paul Watson is making waves with gorgeous Sia Barbi – one of the famous Playboy Playmate Barbi Twins.

But the 63-year-old environmental activist and the 51-year-old beauty have to carry on their romance in secret because Watson is a wanted man! “Paul is Sia’s dream man, but they have to be careful,” said an insider.

A founding member of Greenpeace, Paul became an inspiration to millions with his “Whale Wars” show on animal Planet, which tracked his high seas adventures as he attempted to stop whalers from slaughtering the world’s largest mammals.

He was first smitten With Sia, an ardent conservationist, in 2010 when she and her identical sister Shane joined other celebrities to campaign against seal hunting in Canada.

“Paul thanked the Barbi Twins for helping protest the seal hunt and for their work on the ‘save a seal’ campaign,” said the insider. Sia and Paul became friends, and recently the two got together at a Beverly hills restaurant.

Afterward, Paul sent her a special thank you gift for all her hard work – a plush-toy dolphin made from recycled items.

“Paul can appear gruff and blustery on TV, but in real life, he was shy and gentle with Sia,” said the insider.

Still, the romance sailed into choppy seas because the international police organization Interpol issued a warrant for Paul’s arrest for interfering with whalers from Japan and Costa Rica.

Last October, Paul arrived in the United States after spending 15 months at sea to avoid arrest. But because of his legal difficulties, he was grounded from “Whale Wars.”

Meanwhile, Costa Rica has issued an extradition request to American authorities, but luckily for Paul and Sia, the U.S. government hasn’t acted on it…yet.

“Now Sia and Paul have to carry on their affair in secret,” said the insider. “They can’t let anyone know when they’re going to get together for fear that he’ll get arrested and extradited.”