Kim, Simon and Sienna Brown sold their six-bedroomed house in Aylesbury, gave away most of their possessions and purchased their fabulous yacht, "Britican", a 56 foot Oyster to embark on there exciting, three year family adventure.
During her round-the-world adventure, Sienna will be educated by on-board home-schooling. This was not without initial trepidation from almost everyone who knew her.
Kim said: "I worried that she would lose her ability to be sociable due to a lack of being with a continuous same-age peer group. I worried that she would lose out on making early childhood friends, but now I am 100% positive that we made the best decision possible regarding Sienna's education."
Research shows that parents all over the world have been, and still are, taking their children out of the mainstream school system. In America, over two million children are being homeschooled and in the UK, around 50,000 - increasing daily with all manner of reasons for doing this.
"The law states that parents must provide an education for their children. It doesn't state that the education must be provided by a school system. So from a legal perspective, if parents want to educate their children themselves, then they can", said Kim.
L-R Sienna Maddison Brown and Kim Brown on board Britican
"Let me give you some examples as to how and what Sienna has been learning. Usually, during the morning after breakfast, my husband or I work on letters and numbers with her. If she's not in the mood, we just colour, read a book or do a puzzle.
"We also take her on cultural visits so she can learn about the countries we are visiting. No matter what, she always spends time learning something. We're currently in Italy. She now counts to ten in Italian, practices saying her Italian pleasantries and learns new words every day."
When it comes to socialising, Sienna is a big hit with everyone. "When we had to stop off in Algeria because of violent storms, the people of Algiers came aboard and were very serious. But as soon as they saw Sienna, the men with rifles quickly smiled and each took a turn holding and kissing her. All she did was come up on deck and smile! It didn't take long for one of the immigration officials to join us for a coffee and teach Sienna about the Sahara desert.
"More recently, when we arrived in Sicily, she befriended a boatload of six Italians moored up next to us. Sienna makes friends with anyone of any age. When we visit a playground, she quickly joins other children and plays along.
"Last week, we spent quite a few days in one place and every day she played for a couple hours with a little boy about two years old. His parents owned the local restaurant and he sat in the corner playing quietly. When Sienna came in, he lit up and the two enjoyed time together."
While in Italy, Sienna celebrated her 4th birthday on board. She was showered with Italian gifts - including a pink Peppa Pig birthday cake bought for her by an Italian family.
Kim added: "I know that Sienna's academic education will be incredible and now I'm starting to believe that her social skills will be quite advanced for her age. She's learning about the beautiful world we live in and the amazing people that inhabit it. I can't imagine any other path for our daughter's education."