Humans and dolphins are known to interact well with each other but these incredible pictures show just how well that relationship has developed.
These amazing pictures show free-diver Leina Sato playing with a pod of spinner dolphins off the coast of Hawaii.
And over the years she has built up such an understanding with the intelligent marine mammals that they now even play games together, chasing and catching leaves.
Stunning: These amazing pictures show free-diver Leina Sato playing with a pod of spinner dolphins off the coast of Hawaii
Connection: Over the years she has built up such an understanding with the intelligent marine mammals that they now even play games together, chasing and catching leaves
She started swimming with them eight years ago and instead of her original intention of studying marine biology, she set up her own charter boat company.
This allowed her to dive with them practically every day for four years and to share her love of them with others.
Leina, 26, was born in Tokyo, but moved to France when she was one and again to Hawaii when she was 15.
She said: 'Dolphins have always been a strong part in Hawaiian life and culture and swimming with them is like completely losing yourself in another world.'
She described a game they now play where the dolphins find leaves floating on the surface and attach them to themselves before diving and playing catch with them.
She said: 'It's a spontaneous game but I have no idea who initiated it first, human or dolphin. It's a beautiful and simple example of interspecies communication through play.
Dedicated: Leina started swimming with dolphins eight years ago and instead of her original intention of studying marine biology, she set up her own charter boat company
Passionate: Setting up the business allowed Leina to dive with them practically every day for four years and to share her love of them with others
'It's basically playing a game of catch with a leaf instead of a ball, and needless to say, it is the dolphin leading the dance since we are so slow and clumsy in comparison.
'The dolphins can be a real tease. They will hook the leaf to their fin or tail and swim slowly, wiggling back and forth, enticing us to follow them in anticipation of the moment they will drop the leaf.
'Many times, during the first drops, they will make a very fast U-turn and snatch the leaf again right in front of your nose, as if saying: "Haha, gotcha!" And then we go again for another round...'
She added: 'They seldom put the leaf in their mouths but will hook it on their pectoral or dorsal fin, their tail, or even on their forehead.
'How they keep it there is a great mystery - the only thing that is certain is that they are extremely agile, and fare much better than us at the game even in the absence of hands.
Well-travelled: Leina, 26, was born in Tokyo, but moved to France when she was one and again to Hawaii when she was 15
Talented: Photographer Bo Pardau, 62 works part time on a dive boat and took these images of Leina
'I remember a friend of mine saying that it was the first time that he'd felt as being a "pet" to another animal
'They are just so sensitive and aware of their movements, it is incredible.'
Talking of how she built up her wonderful relationship with the marine mammals, she said: 'I have been swimming with dolphins regularly since I was 18, but I didn't start developing a strong relationship with them until I was 21.
'Instead of going to college, I was fortunate enough to start a snorkelling/dolphin encounter boat charter company with a friend of mine who used to be a free diving champion, so along with the dolphins, I had wonderful teachers.
'For four years, I spent the better part of my day on or in the ocean, interacting with the spinner dolphin population, or with other marine mammal species we can find offshore such as pilot whales and false killer whales.'
Different world: This image shows Leina swimming through a group of dolphins
Love: Leina said swimming with dolphins 'is like completely losing yourself in another world'
Mucking about: Leina said the dolphins can be 'a real tease'
Photographer Bo Pardau, 62 works part time on a dive boat. He lives in Hawaii and first met Leina whilst also diving with the dolphins.
He said: 'She is an accomplished free-diver able to get to 30 metres.
'I usually wait for her to drop into a pod, then follow and see what transpires.
'I shoot all ambient light as the dolphins don't enjoy bright strobes and I free-dive too as they're not keen on scuba bubbles either.
'The dolphins are Hawaiian Spinner Dolphins and are called Naia by the Hawaiians.
'They are quite common and run in large pods of anywhere from 10 to 100 strong up and down the coast.
'They hunt all night and come in to shallow sandy bays to socialise, mate, train and nourish the young, then rest in tight groups until the evening.
'They only get to about 6-7 feet but are curious and extremely playful and if you are good in the water and respectful, you can be with them for up to an hour.
'But when they want to be alone again there is nothing you can do to change that and they're gone.'