Should I create a portal with K2,
and I would need for each item (activities) of k2 to include a map with all the activities that are included in the same place.
You'll need to duplicate the data. For example -> you could use hotspots to place the locations and then you could use the content plugin that we provide
{hotspots hotspot=1}-> this would create a map showing hotspot with id 1. You could show this map at the end of each article. But this is all we can do about it right now.