In 1977, a Dutch man named Stefan Denaerde claimed something that even longtime UFO researchers don't usually hear.

Not just that he saw a UFO or was taken, but that he was invited aboard — fully conscious — and given what amounts to a guided tour. And that's not the only detail that makes his story unique.

The witness isn't some random dude — Denaerde is (well, was) a multinational businessman who initially used a pseudonym to protect his privacy. People saw him as trustworthy, someone not given to elaboration.

According to Denaerde, he was sailing in the Netherlands with his family in the mid-60s. During that trip, his compass suddenly malfunctioned, pointing the wrong direction. Immediately after, something weird appeared in the water underneath the boat.

He saw a figure in the water wearing a metallic suit, a figure he thought was a human diver — until he looked closer.

The being had a non-human face, with large, unusual eyes and a helmet-like covering on its head.

Denaerde then noticed a submerged craft approach his vessel from the water. As he watched it curiously, a craft appeared in the sky above the boat. A calming blue light appeared, guiding him as he was taken aboard the craft.

There he was introduced to beings of superior intelligence. They told him they were from a planet called Larga, located about ten light-years from Earth. They communicated using telepathy, and Denaerde emphasized the feeling of being overwhelmed by a more advanced civilization.

Larga is mostly covered with water, the beings said, but is highly populated and efficient. They employ a social system focused on eliminating aggression.

They're basically described as humans — but evolved socially and mentally far beyond us.

Their role on Earth is simply to observe. They decided to limit intervention through selected individuals.

Denaerde says he learned a great deal about our real history from the extraterrestrials. They showed him that human records are built on limited awareness, and what we think is "important" in history may not be.

He was shown a future course of events in store for us if we don't change our ways — and was then shown how fixed we are in our ways, along with the improbability that we will change in time.

The beings said Earth has been observed much longer than we realize.

They spoke of Earth in a clinical manner, emphasizing how much of our behavior is guided by impulse and conflict-based thinking. We misunderstand reality itself, and life exists in many forms we wouldn't recognize.

They also said humanity is technologically developing too fast, although they don't see technology as our problem — we're the problem.

Stefan Denaerde passed away in 2005.

In his book about the experience, Denaerde doesn't sound like a typical fringe figure. His writing is very structured, almost engineering-like in tone. It's enough to make forget you're reading about a UFO.

It's an interesting story, but it's not without its weak points.

One of the bigger ones is likely obvious: where was his family while he was taken aboard the ship? According to his account, his family remained on the boat while he went toward the craft alone. He then spent a significant amount of time inside it.

But his family did not report a dramatic time gap, and there's no account of panic, searching for him, or witnessing the event in detail.

Whether you believe him or not, Denaerde left behind something more frustrating than simple yes-or-no answer. His account refuses to collapse under easy explanations. There's no dramatic aftermath, no sudden fame he seemed to chase, and no tidy resolution that lets you file it away with everything else.

And the worst part is….they didn't seem worried about us at all.