A camera lowered beneath a cruise ship captured a fascinating glimpse of life below the surface—but what appeared after sunset left many viewers uneasy.

Greek photographer Odysseas Froilan recorded the underwater footage in 2021 after deciding to lower a GoPro from a cruise ship to see what was happening beneath the vessel.

The resulting video runs for around seven minutes and proved enormously popular online, accumulating roughly 12 million views.

A peaceful scene beneath the ship

Froilan chose his timing carefully.

The ship had remained stationary long enough for disturbed sediment on the seabed to settle, helping the camera capture a much clearer picture of the underwater environment.

During daylight, the experiment produced a surprisingly peaceful scene. Fish could be seen swimming around the camera, with some appearing curious about the unfamiliar object that had suddenly arrived in their habitat.

For anyone expecting something frightening beneath such a huge vessel, the first part of the footage was relatively uneventful.

That changed once darkness arrived.

Sharks emerge from the darkness.

When Froilan lowered the camera after nightfall, the underwater environment looked considerably different.

Sharks began appearing in the GoPro footage. One moved rapidly through the illuminated area before disappearing again, while another, much larger shark gradually became visible as it approached from the surrounding darkness.

The contrast between the calm daytime footage and the nighttime encounter became one of the video's most memorable moments.

It also prompted strong reactions from viewers, particularly those already uncomfortable with the idea of deep or dark water.

Some commenters said the daytime footage initially made the ocean appear surprisingly inviting, only for the nighttime scenes to change their minds completely.

Others were fascinated by a shark seemingly materializing from an otherwise dark, empty background.

The footage even prompted jokes about why cruise passengers might prefer the ship's swimming pool to taking a spontaneous dip in the sea.

How the footage was captured

Getting a usable recording from beneath the ship required more than simply throwing a camera into the water.

Froilan later explained that he placed the GoPro inside a protective housing capable of handling the underwater pressure. He also built basic stabilizers to prevent the camera from rolling as it descended.

Weather conditions were important as well. He waited for conditions with little wind or current so the camera would remain relatively stable.

The GoPro was connected to a fishing line, allowing him to lower it until he could tell when it had reached the seabed.

One major limitation: Froilan couldn't watch what the camera was recording in real time. He had to retrieve the GoPro before he could see what it had captured.

What began as a personal experiment to see what existed beneath the ship ultimately produced footage interesting enough for him to share publicly.

Years later, millions of views suggest plenty of other people were just as curious — although after seeing what cruises beneath the surface at night, some viewers may be perfectly happy staying onboard.