Slovenia has a coast that's approximately 46km long. The bad news is if every Slovene decides to go to the seaside, you'll have to take turns to get in the water. But not everybody likes the sea so Iv'e always had enough space to launch my sea kayak. Good news? I can paddle the whole national coast in one day and I know a guy that did it twice. You would have to visit Bosnia or Monaco to top that result. Useless statistics aside, although it's short it has enough potencial to plan a weekend trip or a day trip if you're already in the country paddling somewhere on a river or lake.
If you would like to explore the whole coast you should start in Debeli rtič, the most northern part of the coast. The road will take you to a small cove above the peninsula. From here you can explore the Italian coast further north, but you'll soon hit the industrial part of Gulf of Trieste (Tržaški zaliv) so it's better to head south to Ankaran. You can easily climb out of your kayak in every city to take a break and cruise the old town before you continue. You won't escape the industry here either as the next city is Koper with its port. Make sure you stay away from the port and cross to Izola safely. Once you pass the marina the more isolated stretch begins, first with the natural reserve of Strunjan with its cliffs and the first salt pans Strunjanske soline). After a few smaller holiday resorts and camps you'll see a peninsula with a church and the old town of Piran spreading down to the shore. The small concrete plate? with stairs can be used to 'park & go'. If you climb up to the rampart? you might spot dolphins on the open sea. But if not you'll at least be able to see where you came from and what lies in front of you. The land that you see southwest of Piran is already Croatian Savudrija. As you continue down the coast you will come to Portorož. Portorož is more touristy with bigger hotel complexes. Once you pass the marina at Lucija you should see the channel of salt pans of Sečovlje around the corner. There's a small museum dedicated to the craft of producing salt by trapping the sea and letting the water evaporate. You can buy a package of salt there if you feel you don't have enough of it on your clothes and gear. The specialty of the salt pans is 'Salt flower' (Solni cvet), crystals of salt that get hand picked, never touch the ground and build up only when there's no wind. That should satisfy the gourmet in you and the last 46km should satisfy the paddler in you. If not just turn around 180' and there's another 46km of wonderful coast in front of you. Bon voyage!