Nearby exit Crikvenica to Vine Valley (VInodolska dolina) - you'll see firemen post on that road look for mountaineers markers and after 200 m you'll find ---- LOVE ROAD (Ljubavna cestica)!!! Road is not correctly name for that waht you've find, because, it is small path on the top of small mountain with ruins of castle ''Badanj''.
Great view on part of Vine Valley!
After mountaineering (not so hard), the best is to go swimming back to Crikvenica.
Equipment: Trekking shoes. Long jeans - beware of snakes in summer (especially if terrain is rocky), sunglasses, photo camera, skin creme factor 30 or more. ;-)
For good mountain bikers it is nice attraction.
Obviously you can swim in the sea.
Anyway for swimming games, they use to realize a kind of swimming pool into the sea by the use of floatings.