If you'd like some outdoor adventure, we recommend visiting Gangsastoppen. No easy stroll around the block, this hike is fantastic for some mid-vacation exercise.
You're spoiled for sightseeing choice when staying in Harstad. Gangsastoppen is an ideal place to kick off here, but there are loads of other interesting sights to explore. Trondenes Historical Centre, Trondenes Church, and Grottebadet Waterpark are not far from the steep landmass and will top off your day nicely.