The sea kayaking possibilities are limitless. With an inflatable kayak the use of buses and ferries allows one way tours. Although wild camping is officially not allowed, there are amazing beaches than can be used for discreet overnight stops.
There is surprisingly little information available about kayak routes and logistics.
Almost every resort has basic but reasonable sit on top kayaks available to rent. In good weather they are adequate for even a mutli-day tour.
More professional kayaks are harder to rent. The only place I know of is Sea Kayak Croatia based in Banjol, very close to Rab town on Rab island. Rab town is accessible by both bus and by the catamaran from Rijeka. Banjol is walking distance from Rab town. They organise commercial tours but also rent out their kayaks. Their website is also a good place to get ideas of the better places to kayak in the Kvarner region.
Inflatable kayaks are an ideal option if you want to bring you own kayak. The rocks are sharp but so far I have not had a puncture. The beauty is that they can be carried on buses opening endless possibilities of one way tours.
While I am not a particularly experienced kayaker these are my recommendations. I do not have gpx files for these routes but should be easy to follow.
Rijeka – Opatija
The simplest and most obvious route is to kayak between Rijeka and Opatija. The trip one way is about 10 km, passing several beaches, the Kantrida stadium and also ship yards. A local bus route runs between the two towns, number 32, every 35 minutes (you need a 3 zone ticket). However these buses can be very busy and getting even a packed inflatable kayak onboard might not be easy. However intercity buses between Rijeka and anywhere in Istria almost all stop in Opatija. It’s a little annoying to pay the 8 kuna baggage charge for a 15 minute trip but probably worth it.
Going south from Rijeka along Kostrena to Bakarac or even to Krk island are also obvious routes and served by buses.
This is a fantastic route. it could be done in one long day or you can take advantage of the incredible beaches on the south west side to make an overnight stop – technical illegal so be discreet. The north east side consists of vertical cliffs, there are few places to stop so I prefer to go around clockwise to get take advantage of the beaches later in the day. Start anywhere on the beach in Baska and head out. There are several Autotrans buses running to and from Rijeka via Krk town.
I haven’t done it but the section but the coastline between Baska and Vrbnik is wild and undeveloped and an obvious extension to this route, or could be done as a route in tis own right. There is a limited bus service to Vrbnik from Rijeka ad Krk town.
Around the northern tip of Cres island
I haven’t done this yet but would love to. The route starts in the port town of Porozina, which can be accessed by the morning Autotrans bus from Rijeka to Cres town. It goes around the northern tip of the island which is totally uninhabited. The first real stopping point is Beli. There is a campsite by the beach where water is available. the town itself is a steep 10 minute walk up the hill but worth a visit. There is a hotel in Beli. Otherwise use the official campsite or find a beach anywhere along the coast line. The next stage is to Merag where there is a ferry to the island of Krk. Autotrans bus run from Cres town to Rijeka. It is not easy to get water on this trip apart form in Beli so carry plenty. Even in Merag the public toilets flush with alt water. The ferry café does sell bottled water at extortionate prices.
An obvious extension to the route would be to circumnavigate the island of Plavnik just of the coast by Merag.