Suomenlinna, a UNESCO World Heritage site, is a sea fortress built on six islands at the entrance to Helsinki harbor. Accessible by a short ferry ride, it offers historical ramparts, museums, tunnels, and scenic views. While parts of the fortress have cobblestone paths and are challenging for wheelchairs, efforts have been made to improve accessibility. Suomenlinna is suitable for both solo exploration and guided tours, which provide deeper insights into its history. The fortress is open year-round, but some museums and services may have limited hours during the off-season (winter). A visit typically lasts 3-5 hours, excluding travel time. The ferry ticket is relatively inexpensive, but museum entrance fees and potential tour costs should be considered. Wear comfortable shoes and be prepared for varying weather conditions.