Queen Maxima of the Netherlands looked effortlessly chic in a more casual outfit than usual as she went out birdwatching during a visit to Fort Amsterdam, St Maarten.

The Queen, 51, tread lightly as she joined a birding expedition earlier today, which hoped to locate a brown pelican, the island's national bird.

King Willem-Alexander, 54, joined his wife on the outing and looked to be enjoying himself as the couple were shown around the picturesque area by guides.

Their daughter, the Princess of Orange, also listened intently as they were shown around the historic town, on what is the family's second and final day in St Maarten.

St Maarten is the royal family's fourth stop in their two-week-long tour of the Dutch Caribbean, a trip which has been designed to introduce Princess Catharina-Amalia, 19, to the region.

Sunny weather greeted the royal party to Fort Amsterdam, where they spent the day learning about its history and taking in the stunning scenery.

Queen Maxima's outfit matched the golden rays, with her canary yellow trousers perfectly appropriate for the birdwatching exercise.

She paired her bright culottes with a crisp white shirt featuring coordinated gold embroidery and a rattan handbag with a gold chain. 

The Queen donned more practical footwear than the stilettos she has worn during the trip, going for a pair of suede beige pumps instead.

In contrast to the expensive diamond and sapphire broach and earrings she wore during a tour of St Maarten's capital, Philipsburg, yesterday, the Queen opted for a more rustic jewellery set.

Mirroring the coastal setting, Maxima completed her look with a gold necklace featuring seashells, with earrings to match.

One picture shows that there was a pair of heels at the ready, likely for the Queen or Princess to swap into, just in case.

Princess Catharina-Amalia opted for a pair of classic white trainers as they walked around the grassy area in search of rare birds.

The Princess of Orange had on a cool patchwork shirt in various black and turquoise prints, which she styled with dark navy wide leg trousers.

Maxima and Catharina-Amalia kept the bright sun out of their eyes with their trusty sunglasses, which have made plenty of appearances throughout the trip so far.

Meanwhile, the Dutch King looked relaxed as he wore a blue check shirt, unbuttoned at the top in the high temperatures, with vivid blue trousers and dress shoes.

The family were shown around by various experts and guides, and listened intently as they were informed about the wildlife on the island. 

The royal party began to look a tad windswept as a sea breeze hit the coastal area they were exploring.

Fortunately, a member of staff was on hand to fix Maxima's perfectly preened up do, a look she has become known for during her tour of the Dutch Caribbean.

The family arrived for the excursion in a bright red bus, which Queen Maxima was pictured getting into.

The mode of transport allowed the family to bring luggage and a change of footwear with them for the hands-on outing.

The remainder of their day was set to be varied, as they were then due to meet members of St Maarten's parliament and youth parliament. 

In Fort Amsterdam, they were then scheduled to visit the White and Yellow Cross residential home for older people and people with a disability to learn about the activities organised for residents. 

After receiving an enthusiastic welcome from youngsters in Philipsburg - which included plenty of hugs and high fives - the family will again meet primary and secondary school pupils at today.

They are planning to visit a science fair, where they watch presentations from schoolchildren about their solutions for reducing plastic waste on the island.

In the afternoon the royals are expected to visit Resources for Community Resilience (R4CR), which delivers World Bank funds to projects aimed at rebuilding St Maarten after the devastation caused by hurricane Irma in 2017. 

The family had a packed schedule for their final day on St Maarten, with other activities they were scheduled to undertake including spending time with youth groups, planting yellow sage, the island's national flower, and watching a baseball tournament.

Finally, in the evening the party will attend a reception hosted by the island's governor.

The royal party has so far travelled to Bonaire, Aruba and Curaçao since they began their tour on 27 January.

They will wrap up their time on St Maarten today and are set to visit St Eustatius and Saba in the coming days.

Until 2010, all of the islands, with the exception of Aruba, were part of the Dutch Antilles - an entity that was dissolved and its residents given the choice of independence or integration.

The arrangement is similar to that between the Commonwealth Realms, all of which have Britain's monarch as head of state but have separate directly elected parliaments.