Bald penguin given wetsuit to prevent sunburn
Unlike all his fellow Humboldt penguins, who lose their old feathers over a few weeks to make way for a fresh set, Ralph's fell out in just one day.
And with nothing to protect him from the weather he was at risk of severe sun burn.
He faced spending a depressing three weeks indoors, away from his group and his young chicks.
But keepers took pity on him and fashioned his own wetsuit from the leg of a suit which was donated by a member of staff's husband.
The nine-year-old penguin couldn't be happier with his new clothes, which have caused a stir at his enclosure in Marwell Wildlife, near Winchester, Hants.
Helen Jeffreys, from Marwell Wildlife, said: "Ralph's really taken to his new suit, he's doing really well.
"He doesn't really seem to notice the difference - he's swimming around the enclosure with all the other penguins as usual.
"It's not inhibiting him in any way and it's not bothering him. He's just getting on with his daily business.
"All the other penguins, on the other hand, were intrigued by his new clothes they spent a good while checking him out.
"But when they realised it was still Ralph under the suit they seemed quite happy and don't really pay it any attention anymore."
When penguins moult over a period of around three weeks every year their old feathers are replaced with a new, clean set.
But Ralph has baffled keepers by losing all his feathers in just one day, leaving him strangely bald apart from his head.
David White, who is assistant manager of Penguin World at Marwell, said he and colleagues thought about covering Ralph in suncream before hitting on the wetsuit idea.
Mr White, 31, said: "We noticed he was getting pink and feared suncream would just wash off so we decided to try to make him a wetsuit.
"We used the leg of a man's wetsuit and cut a holes in it for his head and wings.
"It works really well. We thought he would try to peck it off but Ralph seems to love it.
"He's been bombing around in it and acting like a normal penguin, although the others have been giving him a few odd looks. I think they might actually want one now.
"It's certainly a strange sight and Ralph must be the first scuba penguin but he seems so at ease that we've been thinking maybe we should get him a mask and snorkel as well.
"Ralph is perfectly healthy so we don't know why his feathers all drop out at once.
"If we hadn't come up with the wetsuit we would have had to keep him inside to stop him burning.
"That would have made him really miserable because penguins are such sociable creatures. This way he can happily mess around with the rest of the group."
Ralph will now wear his suit for around three weeks while his new feathers grow.
Miss Jeffreys added: "Ralph was so bald he was at real risk of getting sunburned on a sunny day.
"In the past the keepers have kept him indoors for around three weeks until his new feathers have come through.
"But that wasn't any fun for him. He couldn't be with his group and this year he's got two chicks to look after so we just couldn't separate them.
"One of the keepers had the idea of making him his very own wetsuit.
"The material is perfect because it allowed him to go into the water and it's flexible so he could still use his flippers and allow him to have a scratch.
"The keepers didn't have any trouble getting the suit on him - Ralph didn't mind at all."
Visitors are already flocking in to his enclosure to see Ralph parading around.
Miss Jeffreys said: "All the visitors are fascinated by Ralph's clothes - he's causing a bit of a stir.
"He's the only one out of 30 penguins with a special suit so he certainly stands out.
"We get lots of questions from them - they want to know what he's wearing and why or ask if he's a new breed!
"Everyone has commented on how cute he looks. He's certainly become a favourite and I think he'll become a bit of a star now."
Humboldt penguins are native to South America, breeding in coastal Peru and Chile.
They can live for around 30 years in captivity.