Simon and Carla Fowler are anchored in their catamaran about 650 feet off a deserted beach in the Bahamas, and they have a message for anyone locked down on land who wishes that they too could be self-isolating on the water.

“Being out here in a pandemic is actually a lot harder and more stressful than you might think,” said Mr. Fowler, a 60-year-old British events organizer who has spent the last two years living at sea with his Portuguese-born wife on their 40-foot catamaran.

“It is the most depressing time we have had in two years,” he said. “It has been quite nasty.”

Locals fearing infection have become less welcoming to cruisers like the Fowlers over the last six weeks. Ports and borders have begun closing, supplies have become harder to find, and the couple have to abide by the same social distancing restrictions in place on land, meaning they can no longer socialize with other sailors.

The seas may be the ultimate escape and self-isolating destination, but people aboard everything from solo craft to superyachts say the tranquillity of the waves has come with logistical hurdles and ethical dilemmas. And then there is the bullhorn of social media: the blaring comments and tweets calling them entitled, clueless about the serious struggles of the day.

On March 28, David Geffen, the Hollywood billionaire, posted to Instagram a photo of the Caribbean sunset from his $590 million yacht, Rising Sun, with the message “Isolated in the Grenadines avoiding the virus.” The response from many was furious enough to make other superyacht owners, already a secretive bunch, even less disclosing of their whereabouts.

Mr. Fowler suffered his own online kicking after noting on Facebook that he and his wife plan to flee the looming hurricane season by making the weeklong journey to Bermuda, where he hopes to catch up with an old friend.

“I got an absolute tsunami of abuse saying how selfish I was and I shouldn’t be going anywhere or visiting anyone,” he said. “People were vulgar and vile and saying how horrible we are and I got really upset.”

He said he can understand how people are frustrated at being isolated, often in small spaces on land, “but they think we are much better off than we are.”

Leisure sailing is still permitted in some areas of the United States, including parts of Florida, certain areas in New England and San Francisco. But in the Mediterranean almost all private boating has shut down, and cruising hot spots such as the Caribbean and South Pacific are imposing restrictions that often change day by day and leave sailors unsure of where they can go.

Some superyacht owners have managed to get to sea, but brokers say that most charters have been canceled and thousands of boats are locked in marinas or anchored off foreign coastlines.

Ms. Fowler, a 55-year-old former personal assistant to a lawyer, said the only advantage she and her husband have over the homebound is their view of a nearby beach called Spoil Cay. “It’s beautiful but we’re not allowed on shore,” she said. “And we can’t just go for a jog or nick down to the shops like a lot of people.”

No One in Their Wake — Except Online

Bobby White, a sailing blogger from the United States who is now anchored in the U.S. Virgin Islands, agreed that there is a latent vein of social media hostility from “locked-ins” but said the traffic for his “Sailing Doodles” YouTube videos has soared as frustrated armchair sailors follow his trip.

“We were averaging about 3 to 3.5 million views a month, and just in the last two months that has gone over six million views a month,” he said. “I think people are bored stuck at home and have nothing better to do than watch YouTube so that’s great for me.”

Mr. White, 42, has been sailing full-time for three and half years and lives on revenue from the traffic to his YouTube videos.

“I understand that some people are going to be negative so I try not to post too much of: ‘Hey look at me, I am having fun out on the water,’” he said, “because I think maybe people are sensitive to that right now.”

“Most people think, ‘Man, that’s really cool I get to live vicariously through you while I’m stuck in my apartment.’ So I try not to listen to the bad stuff too much.”

Mr. White is sharing his 62-foot CT56 monohull yacht with his Canadian friends Edith Briel and Taylor Francis, and their itinerary has been upended by the coronavirus restrictions and quarantines imposed by various islands.

“We had to leave Puerto Rico because they closed down all marina services and we had some problems with our boat,” he said. “If a technician got caught coming out to your boat, they got fined $5,000.”

“I am supposed to have the boat hauled out of the water in Grenada for hurricane season, but I’m not going there now because who knows what’s going to happen.”

Mr. White said the uncertainty is tough, “but I would rather be here than locked down on land. At least I can jump off my boat and go swimming. If I was in New York City stuck in an apartment watching Netflix all day I think I would go crazy.”

A major problem amid the access restrictions across the Caribbean is that insurers compel cruising vessels to leave the hurricane zone by certain dates — June 1 for the Fowlers and July 1 for Mr. White — and many skippers do not know where they will be accepted.

Mr. White said the Caribbean is already eerily quiet “because a lot of boats have left and the crewed charter boats are just sitting out on moorings hanging out doing nothing.”

Yachts With Everything but Guests

One of the few superyachts still in the British Virgin Islands is the 155-foot motor yacht Loon, which is anchored in North Sound bay.

The crew of 10 has the usual array of water toys, plenty of fuel and several months’ worth of expensive food and wine. The only thing missing? Guests, because the local lockdown means nobody can reach the vessel.

“The next charter on our books that hasn’t canceled is May 11 in the Bahamas, but right now I’m not sure that we are going to be able to get there,” said Paul Clarke, the skipper.

The last guests aboard were a three-generation family of 10 from Chicago, who spent a week aboard until March 21.

“They were supposed to fly down commercial, but for the safety of the crew I requested that they don’t expose themselves to commercial travel so they ended up chartering a jet down to the vessel,” Mr. Clarke said. “Being at anchor on a superyacht anywhere in the world right now is one of the safest places you can be, but you have to get here first.”

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 Sailogy.com, 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 Sailogy.com’s weekly prices stretch from $33,000 to $220,000, with an average of about $80,000.

Remember to Pack the School Uniform, Junior

“We’re still offering charters all around the world, and once on board there are no safety concerns,” Mr. Accardo said.

Sailogy.com and many other charter companies now have more flexibility options and cancellation protection to encourage customers to make new bookings.

Jonathan Beckett, the chief executive of Burgess Yachts, said that apart from helping some luxury boat owners take their families to sea “to weather the storm” of the virus, his firm has also organized three or four “isolation charters” for customers looking to lock down by anchoring in a pleasant spot.

“One was for four weeks but is likely to extend, I think,” he said. “One was for eight weeks and I think will also extend if the crisis continues.”

One Burgess client, a family, is dealing with their son’s schooling by having him get up at 4 a.m. for an online lesson with a teacher back in his home time zone, dressed in his school uniform to encourage routine.

Another family, renting “quite a sizable yacht,” is supplementing their home schooling with cooking lessons from the chef and time in the engine room with the engineer.

Mr. Beckett said his firm has the Olivia, a 226-foot explorer yacht, available in Monaco for sale or charter with a 15,000-mile range and four or five months of supplies onboard.

“Someone could step on there and go off for three or four months into the Indian Ocean or into the Pacific and just sort of chill out and isolate and wait until the pandemic passes,” he said.

But Mr. Beckett said Burgess Yachts was not actively marketing immediate charters, and several other brokers and tour operators told The Times they thought it was irresponsible to offer charters at this time.

Daniel Ziriakus, the president of Northrop & Johnson, a leading yacht agency, said some brokers were offering “escape right now” charters but he believed that was merely “a marketing ploy” because curbs on flights and ports made it almost impossible to do trips at the moment.

“And you are probably endangering your clients and the crew,” he said. “Right now people should stay home and hunker down.”

One 90-year-old owner of a superyacht managed by Northrop & Johnson retreated to his boat some weeks ago because he thought it was the safest place for a vulnerable person, but it has since become harder even to travel to a marina, Mr. Ziriakus said.

Julia Simpson, a broker with SuperYachtsMonaco, said that a few weeks ago her firm was open to charters “but it is not something we would be encouraging people to do now” because people should be staying in their homes.

Henry Cookson, the founder of Cookson Adventures, said he would not want to launch any tours right now that involved people passing through airports and marinas.

“How do you ensure the safety of your crew unless you can physically ensure that the guests have been under full quarantine and had the right tests?” he said. “Even getting tests I think is slightly unethical because there is a huge demand for them for front-line health workers.”

Not every broker thinks people should stay ashore. Bob Denison, the founder of Denison Yachting in Fort Lauderdale, Fla., defended “locking down on water” as a safe way for people to maintain their morale. He also said that although San Diego and some other parts of the United States had curbed boating, many coastlines were still busy.

“There are a great number of people who own yachts who are using them as a second place to responsibly do the social distancing thing,” he said.

His firm has sold several boats in recent days to people frustrated by the lockdown, he said, and had a strong response to two “virtual” boat shows aimed at locked-down armchair sailors.

Britta Fjelstrom, a high school physical education teacher who lives on her 38-foot Nantucket Island sailboat in a marina on San Francisco Bay, said her own answer to that frustration was to sail out recently and anchor in the bay for five nights as a way of “taking control” of the lockdown.

“It was self-isolation on steroids, but it felt like I had chosen it rather than being trapped,” she said.

Ms. Fjelstrom, 46, described it as “like an island holiday”: She spent much of her time reading in a hammock and playing a ukulele in the sea air.

But she was not exactly in remote Tahiti. Anchored near the base of the Bay Bridge, she was within earshot of traffic the whole time.