Aland Islands dive sites

The Kronprins Gustav Adolf was a Swedish naval vessel that sank in the waters of the Aland archipelago in the 18th century. The ship was part of the Swedish navy during a period of frequent naval conflicts in the Baltic. The cold, brackish water of the Baltic Sea has preserved the wreck remarkably well, as the low salinity inhibits the shipworm (Teredo navalis) that destroys wooden wrecks in more saline waters. The wreck was discovered by local divers and has since become one of Finland's most significant underwater heritage sites.

This is an advanced dive requiring a minimum of Advanced Open Water certification, though Deep Diver specialty or technical diving certification is strongly recommended given the 42-meter maximum depth. A drysuit is absolutely mandatory, as water temperatures at depth range from 2 to 6 degrees Celsius even in summer. Twin tanks or sidemount configuration with adequate gas planning for the depth and cold are essential. Penetration requires wreck diver certification and appropriate equipment including reels, redundant lights, and stage bottles for decompression.

Diving the Kronprins Gustav Adolf is typically arranged through dive operators based in Mariehamn on the Aland Islands. The wreck site requires a boat trip and experienced local guides who know the exact location and current conditions. The diving season is limited to June through August when weather conditions are most favorable. Advance booking is recommended as trips depend on weather windows and group sizes. Some operators offer multi-dive packages combining this wreck with other Aland shipwrecks.