Stuart Gravenell, 53, was walking through the Upper Rock Nature Reserve with his son, Bradley, when he was attacked.
A pack of apes charged at them, and one male sunk his teeth into Stuart's forearm and shook its head, opening up two bloody wounds.
Stuart collapsed and was rushed to hospital, where nurses said it was the worst injury inflicted by a local ape that they'd ever seen.
Stuart, a retired IT worker, told the Gloucester Citizen: "You just wouldn't believe how traumatic it was. It was a very very upsetting experience.
"It was supposed to be a nice family holiday and it was totally ruined.
"I have no recollection of the actual incident - I think I must have blocked it out."
World's deadliest animals
British tourist 'sexually assaulted' by Gibraltar monkeys
Although they might look cumbersome and cute, hippos are actually one of the most feared animals in Africa, and can outrun a human. When a male feels its territory is threatened, or a female thinks her offspring her in danger, these animals can be particularly dangerous. And with huge teeth and mouth that can open four feet wide, it's a good idea to steer clear. Kills: An estimated 100-150 people a year. Deadly technique: Hippos will charge, trample and gore its victims, and have been known to upturn boats and canoes without warning. Lives in: Africa
Many people might not realise that the cape buffalo is one of the most dangerous animals in Africa, and will react with force when it feels threatened. These beasts can weigh up to 1.5 tons and stand at 1.7 metres high; they're so intimidating that even lions don't usually consider them dinner. Cape buffalos will charge, and then gore its victim to death with its impressive horns. Kills: An estimated 200 people a year. Deadly technique: These animals will charge and gore their victims to death with their huge horns. Lives in: Africa
Out of the world's 2,000 species of snake, around 250 are thought to be capable of killing a man. The Asian cobra does not have the deadliest venom, but is believed to be responsible for the biggest portion of the thousands of snakebite deaths every year. In Africa, the black mamba is the largest venomous snake and, during an attack, can strike up to 12 times, each time delivering enough neuro and cardio-toxic venom to kill a dozen men within 1 hour. Kills: An estimated 50-125,000 people a year. Deadly technique: A snake will use its fangs to pierce the skin and inject its paralysing venom. Lives in: Africa, Asia, Australia, North America
Box jellyfish can have up to 60 tentacles as long as 15 feet. And each tentacle contains enough venom to kill 50 humans, making it one of the most venomous marine creatures in the world. If stung, a box jellyfish can kill a man within minutes. Kills: An estimated 100 people a year. Deadly technique: Jellyfish use their tentacles to pump venom and paralyse its prey. Deaths in humans are usually a result of cardiac arrest. Lives in: Northern Australia, Papua New Guinea, Malaysia, Indonesia, the Philippines, Thailand and Vietnam.
Apart from humans, the mosquito is the deadliest creature on the planet. It kills millions of people every year through the spread of diseases like malaria, yellow fever, and dengue fever. Many of the malaria victims are children under the age of five. Kills: Two to three million people a year. Deadly technique: Female mosquitos pierce the skin with serrated mouth parts, and inject a saliva with a thinning agent to liquidise the blood. Lives in: Worldwide, more harmful in Africa, Asia and North America
The great white shark, which can grow up to six metres in length and weigh up to five tons, seems to have the most ferocious reputation. But, while they have been known to attack humans, most of these incidents are thought to be 'test bites', where the animal is deciphering whether he wants to eat you. And, generally, they humans are not on the menu. It is thought the aggressive bull shark is responsible for the most attacks on people. Out of the 360 shark species, only four are known killers: the great white, the bull, tiger, and the oceanic white tip. Kills: An estimated 100 people a year. Deadly technique: Sharks use their razor-sharp teeth to rip chunks out of its victims. Great whites usually take a big single bite, drag their victims into deeper waters, and wait until the prey bleeds to death before they eat it. Lives in: Florida, Australia, Hawaii and South Africa.
The are lots of different species of bear, but the polar, black and grizzly are the deadliest. Native to the Arctic, polar bears could decapitate a human being with one swipe of their massive paws. Bears generally attack when they are hungry, so it's a good idea to keep food away from your camp. Kills: An estimated 5 to 10 people a year. Deadly technique: Bear will use their teeth and claws to maul and trample their victims. Lives in: North America, Canada, North Pole, and Russia.
Crocodiles have been around for 200 million years, and are fearsome predators. The saltwater crocodile, or saltie, is the largest living reptile in the world, and can grow up to 21ft long and weigh 1.6 tons. These animals can run extremely fast on land, and, in the water, can swim as fast as dolphin. Many fatalities occur when people are washing or gathering food near river banks. Kills: An estimated 600-800 people a year. Deadly technique: Crocodiles will grab their victims with terrifying speed, and often launch into a 'death roll', weakening its prey, dragging it under water and drowning the victim. Lives in: Africa and Australia
Out of the 1,500 species of scorpion, the African spitting scorpion is thought to be the most deadly, and can spray its venom up to a metre. Arounf 25 species of scorpion are thought to be deadly to humans. Kills: An estimated 800-2,000 people a year. Deadly technique: Scorpions use their tail stingers to paralyse their prey with venom. Lives in: Worldwide; particularly Africa, the Americas and Central Asia.
Weighing in at up to eight tons, although beautiful creatures, elephants can be lethal. African elephants in particular can be aggressive, especially older bulls and young males. These creatures, unsurprisingly, are more aggressive in areas where poaching is rife or when their habitat is threatened. Kills: An estimated 300-500 people a year. Deadly technique: Most human deaths are result of the elephant trampling on its victim. Lives in: Africa and India
African lions are the biggest of the big cats, and are known to kill around 70 people in Tanzania alone every year. With the destruction of their habitat, human attacks by leopards in India, and the North American mountain lion are thought to be on the increase. Kills: An estimated 800 people a year. Deadly technique: African lions will often use strangulation to kill their prey, while tigers will attack from the back and aim for the jugular, and mountain lions will maul their victims. Lives in: Africa, North America, and India
The best beaches in Spain (according to Tripadvisor)
British tourist 'sexually assaulted' by Gibraltar monkeys
Endless sea, fine sand, spectacular views and Ibiza on the horizon. No wonder this beach takes pride of place in Tripadvisor's best beaches in Spain. What visitors say: “You have the sea on both sides, which makes it unique. The views are amazing. The water is crystal clear.”
This beach in Galicia, on the Cantabric coast has been declared a national monument. With its sea caves and natural arches, it's wonderful for exploring at low tide. What visitors say: “The beach itself is gorgeous, but just the view of the sea from the top of the rocks makes one dizzy.”
La Concha, which means 'shell' in Spanish - this beach is shell-shaped - is one of the most famous urban beaches in Europe and one of the loveliest in the Basque Country. What visitors say: "Beautiful scenery and very clean beach. Well worth a visit. If you want a place to recharge your batteries this is it."
This beautiful sandy bay near Cadiz is singled out for its unspoilt beauty. Sun worshippers in this area usually head for the joys of Tarifa, so the beach here remains largely unspoilt (although it's a favourite with Spanish families.) What visitors say: “This is a fantastic empty beach, at least in May.”
The sandy windswept beach on the Peninsula de Jandia is spectacular and gloriously empty even in peak season. The relentless surf pounds the beach all day so it's not for swimmers - but its beauty is undeniable. What reviewers say: "Amazing... I will never forget it." "It's like being in another world."
Being so close to the Strait of Gibraltar, this is precious environment is ideal for bird watching during migration periods, as well as whale watching. "There is nothing bad about this place. Clean sea, excellent food and calm ambiance. Ideal for a romantic walk at dusk," says one reviewer.
With some of the cleanest, clearest water and the softest golden sand in Ibiza. Situated on the west coast of the island, this is also one of the most popular beaches in the area. What visitors say: “Lovely bay, busy though even in October.”
The "jewel in the crown" of Gran Canaria, Playa de las Canteras is a long strip of sand protected by a natural reef that stretches for miles along the bay. Locals say it's one of the Spain's best urban beaches: people flock to this fantastic beach because of its ideal conditions for eater sports, too (the waves at one end are perfect for surfing). Reviewers rave about its cleanliness and "amazing atmosphere"."The best beach in the world," says one.
This beautiful wide, soft stretch on the Atlantic coast boasts miles of fine clean golden sand it's so huge that doesn't feel crowded, even in the height of summer. Plenty of bars and immaculate rest rooms are singled out here too. "This really is a terrific place to spend your day," says one reviewer.
The breathtakingly beautiful wild beaches on the north west coast of the island boast lovely little coves give a deserted feel that is perfect for anyone wishing to get away from it all. There are lots of secluded spots (and plenty of naturism) and plenty of amazing snorkelling in the lagoons. What the reviewers say: "Seemingly endless, beautiful beaches. A perfect mix of volcanic bizarre looking rocks and Sahara sand."