Leo DiCaprio got a big surprise when he was the sole bidder, at $250,000, on artist Walton Ford’s “Pacific Theater” painting at a New York charity event to help endangered turtles.

The actor gamely raised his hand to open the bidding for the huge watercolor, said to be worth $500,000, at hotelier Eric Goode’s Turtle Ball at the Bowery Hotel on Monday.

But a hush descended when none of the other guests, including Ted Danson, Richard Branson, Patti Smith, Naomi Watts, Liev Schreiber, Graydon Carter and honoree Robert Kennedy Jr., raised a hand after Leo placed his bid on the painting, which depicts a fiery bombing raid on a lush island.

DiCaprio, smoking a vaporizer and wearing his trademark newsboy cap, appeared shocked when auctioneer Fisher Stevens announced, “Sold to the man in the cap.”

DiCaprio looked around the room and pointed to art dealer Tico Mugrabi and Christie’s SVP Loic Gouzer, who were seated at his table. We’re told Leo ended up splitting the price tag with Gouzer. “They decided to go in on it together. It remains to be seen who will get to keep the piece of art,” said an insider.

We’re told Gouzer, who has advised DiCaprio on his art collection in the past, only suggested that he buy Ford’s painting. But a source close to the star insisted, “Leo is close friends with the artist and is a huge fan. He already owns three pieces from him, so he was excited to get the painting.

“He’s passionate about environmental issues and was happy to support the Turtle Conservancy because it’s an amazing group.”

DiCaprio has become an avid art collector over the years and owns pieces by Frank Stella, Takashi Murakami, Ed Ruscha and Jean-Michel Basquiat.

“Pacific Theater” was the priciest work sold at the auction, which raised over $700,000. “It was incredible that the artist donated the piece, and it’s great to see the entertainment world and the art world rally to become more aware of species conservation,” said Goode.

Other guests at the Turtle Ball: