Isosaari
Isosaari island · Stor-Holm
60°05.6'N 25°05.6'E
Depth
3–6m
Bottom
sand
Alarm Radius
80m
Holding
Good
Recommended Anchor Alarm Radius
80m
80m for good holding in sand/mud in 3–6m. Open to west across the Gulf of Finland — in westerly conditions above F4, seek shelter in Suomenlinna or Helsinki harbour.
About This Anchorage
Isosaari ('Big Island') is a former military island about 8nm east of Helsinki, recently opened to civilian access after decades of military use. The island retains its WWII-era military infrastructure — bunkers, gun emplacements, barracks, and the characteristic Finnish coastal defence architecture of the 1940s. The island is now managed as a nature and recreation area with marked walking trails through forest and along dramatic granite coastline. The anchorage on the west side gives reasonable shelter in easterly conditions. The Helsinki shipping channel passes close — large vessels are a constant feature of the background. An atmospheric alternative to the more crowded Suomenlinna anchorage.
Protected From
E · SE · NE · N
Exposed To
W · SW · NW
Anchoring Rules
- Anchoring fee
- Free; check current access status with Finnish Defence Forces
- Permit required
- No
Restrictions: Former military island — some areas may still be restricted; check current regulations; stay on marked paths; no removal of military artefacts; Helsinki main channel nearby — maintain watch for large vessels.
Hazards
- !Helsinki main shipping channel passes close — large vessel traffic; maintain constant watch on AIS
- !Open to west and SW across the Gulf of Finland — westerly conditions expose the anchorage
- !Former military island — some areas may be restricted; check current status before visiting
- !Rocks and shoals in approach — use Finnish chart
- !No facilities — completely self-sufficient
Skipper's Tips
- →Isosaari is the alternative to crowded Suomenlinna — far fewer visitors and a more authentic wilderness feel despite proximity to Helsinki
- →The WWII military infrastructure is fascinating to explore — the gun battery positions give excellent views toward Helsinki and Estonia (on clear days)
- →Helsinki's skyline is visible from the island — the Cathedral dome and Temppeliaukio rock church are landmarks on the horizon
- →Early morning fishing around the island rocks is excellent — sea trout and perch frequent the shallow rocks
- →The Helsinki–Tallinn ferry (2.5 hours) passes close to Isosaari — the overnight departures are visible from the anchorage
Facilities
No facilities. Self-sufficient sailing. Seasonal café may operate (check current status). Nearest full provisions at Helsinki (8nm).
Nearest provisions: Helsinki South Harbour (8nm) (8nm)
Best Months & Season
Jun, Jul, Aug
June–August. Check access regulations annually — military island status may change. Good alternative to Suomenlinna for solitude.