In Gdynia, I was not with the goal of a beach holiday, came to the Open Air festival, and the beaches and the sea were a pleasant addition. Of course, this is a resort on an amateur. Baltic is not distinguished by strong heat and comfortable sea. The beaches here are chic - solid sand extending a few kilometers. The beaches are quite wide, so I have never seen people to be like in our Crimea. There is always a place and personal space no one violates. Bathing uncomfortable. You need to pass more than 100 meters so that at least swim is normal. And it is scary. You go, go, go, the shore is farther and becomes scary. And if you still fall into the pit - horror!
Water is pretty warm, which can not be said about air. It is possible to sunbathe in the afternoon, and in the evening the temperature may fall to +12 degrees. And it is in the middle of summer!
In the city itself there is nothing to do. This is a port city, but the port is located on the city center, so it does not interfere with rest on the beach. But right next to the beach there is a parking of yachts (you can learn to manage the yacht), here is a warship in which the museum is now.
Entertainment is especially no, the parks are very boring. There is nothing at all on the weekend, since neither the markets nor shops work, so you have to sit in bars, or walk through the streets. It is good that every evening I was busy with a festival, and then I would have died from boredom.