The author is Professor of Environmental and Geographical Sciences at Bournemouth University, UK.

Unless you are a fan of reading or water sports, building sandcastles is a must for seaside vacations, but how do you make your castle as majestic as it is durable? Fortunately, there is a scientific formula that may help you.

As a sedimentologist, i.e. a specialist in rock deposits left by water, wind and glaciers, in 2004 I began thinking about what kind of beach would be best suited for building sandcastles. I conducted the survey by comparing the sands of the ten most popular beaches in Britain (at the time). Although you can actually build castles on any beach, Torquay ranked first in my ranking with its beautiful red sand.

But once you choose a beach, you still have to find the perfect location. This question is more about individual preferences: some prefer to settle not far from the parking lot, so that they can escape in case of rain, while others prefer near a coffee shop. Still others choose a secluded corner, perhaps better protected from the wind by a natural protrusion.

If you want to build a real fort, it is better if your building is standing. And for that you need hard sand! The strength of sand depends on two factors: the properties of the grains it is made of and the water that allows them to stick together. The more angular the granules, the better aligned they are. However, the more elements that grains of sand convey, the smoother they become. This is why microscopic fragments of seashells are a wise choice for building castles. Finally, the finer the grain, the better it retains water. And the issue of water is crucial to the issue at hand!

If the sand contains too much water, your castle will fall, and if there is too little, it will collapse. So you need to find the right proportions, so that your castle stands straight, and for a long time. It all depends on surface tension of water, or “hydraden meniscus,” the phenomenon that makes it difficult to move a glass of water placed on a soft, moist bolster.

magic formula

Our experience has allowed us to prove that for every eight buckets of dry sand you need one bucket of water to build the perfect sandcastle. Or if you prefer, here’s the magic formula: Water = 0.125 x sand. But if you do not have science materials, do not panic! All you have to do is find a location in the strip of sand between the high tide line – easily spotted by a combination of seaweed and marine debris – and the low tide line. Keep in mind, however, that this area moves during the day, depending on the tides.

The following tip concerns the quality of the tools. In my experience, there is a direct relationship between the age of the build and the size of the excavator and the speed at which boredom begins. Adults find the smaller excavators very frustrating, and the kids love to use the larger excavators, but find them difficult to handle. So that the team atmosphere remains harmonious, so plan a wide range of tools. The size and shape of the bucket is also important. Prefer simple, round buckets to castle-shaped ones with hanging towers. The round bucket will allow you to produce a lot of tricks and details to end up with the monument of your dreams, by activating your imagination.

And as you build, keep thinking about the story, not only the fantasy of the castle and the old fairy tale set, but also the actual story of the sandbox you’re dealing with. Each grain is actually a part of the rock that sums up the long history of extinct mountains and ancient rivers, Dinosaurs spread in swamps and seas, Climates and Events of the Past: Lots of Elements That Tell a StoryThe history of our planet.

You can of course be content with a modest castle, with beautiful towers, ramparts and moats, but the castles that make the difference on the beach and that are the most successful are also the most imposing. Think larger! Pebbles, seashells, driftwood and feathers can decorate your work. And then, let’s be honest: the sandcastle is made to impress. And while there is a little science behind the perfect castle, be sure to have fun building it.