The Estonia ferry sank in the Baltic Sea in 1994, killing 852 people in one of the 20th century’s worst maritime disasters.

After deciding not to salvage the wreck, Sweden, Estonia and Finland agreed in 1995 to designate it a final resting place and make it illegal to disturb the site.

In 2019, a film crew sent a remote-operated submersible to the ship while filming a documentary that aired the following year, revealing a massive hole in the ship’s hull and casting doubt on the findings of an official investigation into the sinking.

The Gothenburg district court found in February 2021 that the documentary’s director Henrik Evertsson and deep-sea analyst Linus Andersson – both Swedes – had committed actions punishable under the so-called “Estonia Law”.

However, it ruled they could not be held accountable since they were on a German-flagged ship in international waters at the time.

While several countries have signed on to the 1995 accord, Germany has not.

But the Göta Court of Appeal on Tuesday sent the case back to the lower court for a retrial. It argued that “the Estonia Law does apply” because the filmmakers are Swedish, even though the dives were conducted from a German boat.

The two could face a fine or up to two years in prison.

The original inquiry into the disaster concluded that it was caused by the bow door of the ship being wrenched open in heavy seas, allowing water to gush into the car deck.

Experts however told the filmmakers that only a massive external force would be strong enough to cause the rupture, raising questions about what really happened.

Survivors and relatives of those killed have fought for over two decades for a fuller investigation, though the countries involved have been reluctant to re-examine the issue.

Following the documentary, the laws banning dives were amended in order to allow a re-examination of the wreck.

In July 2021, Sweden and Estonia opened a fresh investigation.