Mansikkalahti is a local Kotka beach rather than a grand coastal destination, but that makes it useful. In summer it offers a simple place to swim, sit by the water, and enjoy the softer side of a city better known for parks, harbour views, and maritime history.
Bring realistic expectations: the season is short, and the beach is at its best on warm days when locals are using it too. Outside summer, it becomes more of a quiet waterfront walk than a swimming stop.