The flamingo is even more popular on social media, while retailers are also selling giant watermelon slices, lobsters, cacti, pineapples and ice lollies.
Retailers also reported a sales hike thanks to Love Island, where inflatables can be glimpsed in the villa's swimming pool.
But the coastguard agency has issued a warning about the toys, urging people not to take them into the sea.
HM Coastguard duty controller Piers Stanbury said: "We've had people rescued from a number of beaches along Hampshire and Sussex coastline. Each one of them had been using an inflatable. Thankfully, everyone so far has been rescued and is safe."
"We can't stress enough that these inflatables are not suitable for use in the sea. Tide conditions, the wind, any changes in the weather can just take them out beyond safe depths.
"Please, don't use them. Don't take them to the seaside. Inflatables should only be used in swimming pools, not at the coast where they can quickly go from being fun to being potentially deadly."
The 15 rescues took place on Monday. In the unicorn incident, a helicopter was scrambled when the woman drifted into the Solent, a major shipping lane used by passenger, freight and military vessels.
Hillhead Coastguard Rescue Team, based between Portsmouth Harbour and the River Itchen, tweeted: "Tasked to a person blown over 400m from shore into one of the busiest waterways in the world on an inflatable unicorn.
"Luckily, a passing kayaker assisted until Gosport ILB [a patrol craft] recovered the casualty safely to shore."
A team from Hayling Island Lifeboat Station, Hampshire, was called out to another unicorn, only to pass a flamingo on the way and then spot a person in the water who had drifted out to sea in a dinghy and was clinging to a buoy.
Using inflatables at the beach safety adviceWith the #heatwave we are experiencing across the UK and Ireland, you may be tempted to take to the sea with an inflatable. These are designed for pools and not the sea, where they can be easily swept out, but if you do use them at the beach remember to #RespectTheWater. Visit a lifeguarded beach and only use close to the shore in calm conditions and in between the red and yellow flags.
RNLI Blackpool were called out to someone a mile offshore, who had been enjoying a day at the beach with her family, when she was blown out to sea in her inflatable.
Posted by RNLI on Monday, 2 July 2018
Three lifeboats and a helicopter then set out to search the bay, fearing that someone had fallen from the flamingo, but they were stood down before sunset. The Maritime and Coastguard Agency said rescue teams are wasting valuable hours checking abandoned inflatables.
"Some of the inflatables were collected by our teams, some will have made their way over to France," the agency said.
Where once holidaymakers were content with the humble lilo, the demands of social media call for ever more elaborate accessories.'
At John Lewis, the hot weather has seen a rush of sales for deluxe inflatables in the shape of gold-winged unicorns, flamingoes, toucans, swans, peacocks and a tropical island complete with palm tree.
The store's top-seller is the £65 ride-on unicorn, accounting for nearly one in four inflatables purchased, while sales of the lie-on watermelon have risen 172 per cent in the past week. Lisa Rutherford, seasonal buyer at John Lewis, said: "Giant pool inflatables are hot property at the moment, and TV programmes are also influencing customer purchases.
"Since Love Island hit the UK's screens in the last few weeks, we have seen sales soar."
