OK, so technically those are in fact two beaches, but we'll still cover them in the same article, for reasons which should be quite apparent.
Once you get to Žrnovo, there's a wealth of ways you can decide to go to find your perfect beach spot, as Žrnovo is a kind of hub to get to the "defora" beaches (that name comes from the Venetian phrase "el de fora", meaning something like "on the outside", often used on Korčula).
Those perfect coves on the Southern side of the island, where you don't just stumble upon, where you need to actively be willing to go to, are deep , with clean water, protected from the strongest winds, and not overly-populated most days (during the peak of the high-season it's possible that there will be more people on those beaches than you'd wish, but still less so than on more easily accessible beaches). Orlanduša/Bratinja Luka is one of them, located somewhere right in the middle of those "defora" beaches, between Bačva (one of the most popular ones) and Pavja Luka (not very popular, because it's very unaccessible), and Orlanduša is what the Eastern section of the bay is called, while the Western section, going deeper inland is called Bratinja Luka.
It's not easy to get to the beaches, although there are signs directing you to them from Žrnovo Postrana, and it's around 5 km to drive to Orlanduša - with portion of the road being asphalted and some of it being gravel road, going through the vineyards and quite wild portion of Korčula Island. The only place to park your car is some 200 meters from either of the beaches, but your car will be parked in the shade, and the walk to the water is not too steep or demanding. You can also walk to the beach all the way from Žrnovo, of course, if you know your way around with a map, and then it will be somewhat shorter to get to the beach, just remember to bring lots of water with you, as there are no bars or restaurants in either Orlanduša or Bratinja Luka.
Since both beaches are facing South (one of them SW, the other SE), there will be a lot of sun on the beaches in the afternoon, but on both of them you'll be able to find some natural shade if there aren't too many people there, but if that's something that's really important to you, bring your own parasol along, as well as lots of sunscreen. Both beaches are pebble, with lovely entrances to the water and rocky slabs off to the side of the beach, so you can find a spot there if you want to escape the crowd. There are few houses in the area of the beaches, and it's possible to rent them for a vacation stay, if you really need to get away from everything and enjoy as much silence as possible on a busy island.
There will be boats in the bay, smaller and even some larger, as it is a popular spot to get away from the wind, but that shouldn't deter you from swimming from one side of the bay to the other, it's excellent exercise and will give you great view of the wonderful place where you decided to spend the day!
