The "Pool Swimming" activity detail page should show up in "Daily Activity" and "Reports" view, when you've selected
exactly one activity which has pool swimming data (recorded with Garmin 910XT in pool swimming mode or Swimsense watch):

You haven't told us, which swim watch you are using.
If it's a Garmin and the hint above does not help you, zip the imported .FIT file that you had imported and add it to your post, please.