The Baltic Sea anomaly was discovered while the OceanX team was treasure hunting on the floor of the northern Baltic Sea.
Notes on verification
Multiple independent sources (ExplorersWeb, HowStuffWorks, NBC News, Discovery UK, Wikipedia) consistently corroborate that OceanX (Ocean X) team discovered the anomaly while treasure hunting in the Gulf of Bothnia in summer 2011. [cascade flags: aggregator_dropped_primary_exists | tier=silver indep_score=0.833 clusters=3 claim_tier=notable]
Sources
- Baltic Sea anomaly (wikipedia)
- https://www.discoveryuk.com/mysteries/the-baltic-sea-anomaly-natural-formation-or-alien-artefact/ (corroboration)
- https://explorersweb.com/is-the-baltic-sea-anomaly-natural-man-made-a-hoax-we-explore-the-possibilities/ (corroboration)
- https://www.nbcnews.com/news/amp/wbna48844496 (corroboration)