The Seas as the Ultimate Coronavirus Isolation? Not. So. Fast.

Mr. Clarke, who is 37 and from Australia, said the Chicago family concentrated on letting their grandchildren enjoy the water but the adults were glued to news reports of the coronavirus. The tension rose, he said, as the week went on.

“We tried to make sure they had as much fun as possible, but they were obviously worried about what was going on back home, just like everyone in the crew,” he said. “We are not concerned about our own safety because we have been so good with self-isolating but we are all a little worried about friends and family.”

Dirk Uffenkamp, a 53-year-old engineer from Bielefeld, Germany, was also focused on what was happening back home when he and six friends chartered a 48-foot Leopard catamaran in the Seychelles until early March.

Mr. Uffenkamp said his friends seriously considered extending the charter to stay safely isolated.

“But we all have families with partners and children, and the idea was thrown overboard pretty quickly,” he said. “We knew we wanted to fly home.”

That catamaran is still available for charter through the online agency, but the firm’s founder, Manlio Accardo, said the problem is there are no flights to the Seychelles.

The yacht used by Mr. Uffenkamp’s group costs about $16,000 a week, but Mr. Accardo said weekly charters range from $1,500 to $27,000, with an average of about $5,500. In the crewed and luxury market’s weekly prices stretch from $33,000 to $220,000, with an average of about $80,000.