Prince William gifted Finland's President a letter from Queen Elizabeth to mark the country's 100th year of independence.
The 35-year-old royal is currently on a two-day tour of Helsinki where he met head of state Sauli Niinisto and gave him the note which he described as "a message to a good friend".
Elizabeth's message read: "Prince Philip and I send our warmest good wishes to you and to the people of Finland on the occasion of its 100th anniversary.
"We have fond memories of our State visit to Finland in 1976, when we experienced the warm hospitality of Helsinki, Turku and Jyvaskyla.
"In 1976, I spoke about how we in Britain had long associated friendliness with Finland, an association that is no less true 41 years later.
"Over the past four decades our two nations have worked together in many ways - on security, on commerce, on our people-to-people Iinks - always aided by that spirit of friendship.
"I have no doubt that we will continue to build our relationship in this way in the years to come."
William also visited a Helsinki ice rink to see the work of Icehearts - a child welfare charity which helps youngsters from disadvantaged backgrounds feel less excluded - and show off his ice hockey skills.
He later headed to a reception, where he made a speech praising the nation and admitted he was looking forward to learning more about the country.
William said: "I am delighted to be visiting Finland as you celebrate 100 years of Independence - a country that has become a byword for courage, determination and resilience; a country that through its commitment to civil liberties, education and quality of life has become a model to be studied, envied and emulated worldwide.
"I am keen while I am here to learn more about what makes Finland such an admired nation. I am especially looking forward to learning from Finland's experience of promoting wellbeing in society."