Before they leak.

The 170-metre cargo ship S/S Skytteren sank in 1942 at 74 metres depth off Måseskär on the Swedish west coast. The wreck site lies directly adjacent to a sensitive archipelago — both marine fauna and coastlines are at risk. Before our survey, Skytteren ranked number one on HaV's list of the 30 most hazardous wrecks in Swedish waters.

Ocean Discovery's 2020 documentation identified 22 hull holes and a 4.2-metre crack — damage that previous multibeam surveys with lower resolution had not detected. The high accuracy of photogrammetry made them visible. The subsequent remediation recovered 175,000 litres of oil and oil-mixed water.

The survey used ROV, side scan sonar and over 25,000 high-resolution images. Water-parameter measurements showed strong bottom currents and high oxygenation — conditions that drive rapid corrosion.

During summer 2024, six wrecks were documented 25 nautical miles southeast of Karlskrona at 62–64 metres depth: Brise, Bruin, Magdalene, Molund, Monestra and Östanhav. Identification was made possible by overlaying the photogrammetric 3D model with historical GA drawings.

In April 2026, JD-Contractor A/S carried out test drilling on four of these wrecks. The operation read Ocean Discovery's point clouds directly into the EIVA 3D navigation system — the remediation contractor could position drilling equipment with centimetre precision at over 60 metres depth. On Bruin, 15 boreholes were drilled and oil was found in five locations — two bottom tanks (about 43 m³ each) and the engine room. On Magdalene, 19 boreholes were drilled with oil in two tanks on the south side, but only small amounts (up to 1–2 m³). No oil was found in Molund or Östanhav. More than 5 tonnes of ghost fishing gear were also recovered — our photogrammetry let the team trace each trawl net in 3D and plan exact cutting points in advance.

Our documentation cut field time and reduced risk — every drilling position could be planned in advance.

M/S Malmi sank in 1979 en route between Gdynia and Turku. The wreck lies 78 km northeast of Gotska sandön at 172–182 m depth — too deep for divers. Simulations showed that an uncontrolled oil spill could reach Gotska sandön-Salvorev (a Natura 2000 area and national park).

Ocean Discovery's 2019 documentation formed the basis for HaV's remediation decision. During 2023–2024, a specially adapted ROV-based hot-tap system was developed for tank penetration at extreme depth. Oil was recovered from three of six investigated tanks — a total of 44,000 litres of oil and oil-mixed water.

The depth and dramatic technical complexity make the Malmi remediation one of the most advanced underwater operations carried out in Swedish waters.

The tanker Lindesnäs sank in 1957 off Oxelösund carrying 1,732 cubic metres of aviation kerosene. Simulations showed that an uncontrolled spill would reach the Natura 2000 areas Bråviken and Hävringe-Källskären.

Our documentation of the wreck preceded HaV's remediation decision. In August–September 2019, HaV led the remediation together with JD-Contractor A/S — 299,000 litres of oil were recovered from one of Sweden's most hazardous wrecks. The operation cost approximately SEK 21 million funded through the government appropriation for remediation of contaminated areas.

Lindesnäs represents the single largest oil-volume remediation where our documentation served as input.

Every wreck survey combines several techniques to create a measurable digital record.

• Side scan sonar (SSS) — maps the wreck site and surrounding seabed.
• Multibeam echo sounder (MBES) — high-resolution 3D bathymetry of the site and bottom topography.
• ROV-based photogrammetry — 5,000–10,000+ high-resolution images with 70–90 % overlap generate a 3D model at 1.5–2 mm pixel resolution.
• Ultrasonic hull-thickness measurement at representative points — input for assessing structural deterioration.
• Water-parameter measurement with the EXO3 multi-parameter sonde (salinity, temperature, oxygen content) — input for assessing corrosion conditions.

All measurements are geo-referenced to the Swedish coordinate system SWEREF99 TM, enabling direct integration into the remediation contractor's 3D navigation system such as EIVA.