Billionaires are demanding this over-the-top feature for their superyachts

The rite of passage for any billionaire is to get a superyacht - floating palaces where the mega-rich can live in luxury on the sea.

The engineering to build these boats requires cutting-edge technology, including fixed-pitch propellers combined with a Rolls Royce central booster jet, to keep them afloat as well as allowing them to travel at the speed that would be equivalent to a Ferrari on the ground.

The interiors also put some of the world's most famous five star hotels to shame too.

What's even cooler is that when you have the level of fortune that rivals a small country's GDP, you can customise your boat with whatever you want. Considering prices for the smallest yachts, without extra customisation, start from €66 million (£48 million, $74 million), the mega-rich are able to afford some of the craziest customisations.

In an interview with Business Insider, Dutch superyacht builder Heesen Yachts told us that there is one major feature that its clients are demanding to be put on their boats: waterfalls.

Here is a shot of a waterfall placed in one of Heesen Yachts' largest boat - the Kometa. The boat overall is 70 metres in length and can achieve a top speed of almost 30 knots.

But these waterfalls aren't just for aesthetic purposes, they also serve another couple of cool functions as well.

"The big trend at the moment is that clients want bigger platforms to fit more guests and, at the same time, be closer to the water and the surrounding environment," said Sara Gioanola, a manager at Heesen Yachts, to Business Insider. "They are wanting infinity pools, which are pools that give a visual effect of the water extending into the horizon, as well as waterfalls. The waterfalls look beautiful but they can also create a water banner, depending on the amount of water gushing, to enable a privacy shield. They can also be used to project movies onto it."

So imagine if you turned up the water flow on this indoor waterfall, you could watch your movies on it.