An excellent alternative to staying in central Helsinki is near the ferry pier on Suomenlinna. Once a Russian primary school, then a barracks, the red-brick building's dorms occupy bright, high-ceilinged classrooms, while cosy private rooms upstairs have sloping ceilings. There’s a kitchen (and supermarket nearby) and laundry, and the hostel recycles and buys renewable energy.
Breakfast (€7.50) is available with 24 hours' notice, and there's a toy box and games for kids. The place is quite often booked out by groups in term time.