Family mourns death of Robert De Vos Burchart of Switzerland after swim at Gibson Beach in Sagaponack

Robert de Vos Burchart of Switzerland was visiting Gibson Beach in Sagaponack earlier this month with his girlfriend as part of the couple's vacation when he dove into the surf for a swim.

"He was having a fabulous time," Karen Kreps, his girlfriend of about 18 months, recalled Tuesday. "I was just admiring what a strong man he was, and what a good swimmer."

As she watched de Vos Burchart dive into waves multiple times that sunny afternoon, she had no reason to expect he would not emerge.

His daughter, Nathalie de Vos Burchart, who lives in Texas, described her father as "active" — an "avid downhill skier" and tennis player — and "very comfortable" around water.

"He’s a Dutchman, he’s a sailor, he’s always been around water," she said. "He shared that the Atlantic Ocean reminded him of the North Sea. ... From his youth he played water polo competitively in the Netherlands."

All of which made it a mystery why the 73-year-old she called "an adventurer" never reappeared after he went under water about 3:40 p.m. on Oct. 4. Nathalie de Vos Burchart said her father was found unresponsive on the beach about 20 minutes after he disappeared.

Southampton police officers, Bridgehampton Fire Department volunteers led the search,

On Tuesday, Southampton police confirmed Robert de Vos Burchart's death but had no additional information about the cause.

Despite efforts of first responders to administer CPR, de Vos Burchart was pronounced dead at 4:41 p.m. Oct. 4 at Stony Brook Southampton Hospital, his daughter said.

"The way I look at it, my father left this world in a way that pretty much exemplifies him, doing things as if he was still 20 years old in his mind," Nathalie de Vos Burchart said. "But unfortunately he was 73."

Robert de Vos Burchart was born in Amsterdam on Jan. 22, 1951, his daughter said. After getting a master's degree in chemical engineering from University of Twente in Enschede, Netherlands, she said her father became "an adventurer." The family traveled the world for his work in sales and marketing for companies based all across the globe. He met her mother in Illinois, she and her sister, Fabianne, were born in Paris and the family briefly lived in West Africa before settling in Geneva, Switzerland. De Vos Burchart and his wife later divorced.

Despite only dating 18 months, Kreps and de Vos Burchart had known each other for more than 50 years. She said he was "always cheerful" and "positive."

After marriages and divorces, professional paths crossing and departing, the two connected in Geneva and had been together ever since.

"It was the most remarkable relationship of my life," Kreps said. "I’m amazed at how much I loved him and how well we got along."

Robert de Vos Burchart was cremated on Long Island, but his daughter hopes to spread his ashes along the lake behind his apartment in the mountainous ski town of Crans-Montana, Switzerland in January.

"He always lived by a lake," Nathalie de Vos Burchart said.