There are a lot of things to do in the summer, but Italians talk about them a bit differently than English speakers do. The word we will hear all the time in Italy, at least if we're within a two hour drive from the coast, is il mare.
As you can see from the following example, we talk about the beach, because for the most part, we have sandy beaches. But Italy, being a peninsula (penisola in Italian) is surrounded on three coasts by the waters of the Mediterranean Sea, so it's a vital part of the country itself. The sea has different names depending on what part of Italy it touches on.
Infatti, io e Giorgia siamo andate insieme al mare.
In fact, Giorgia and I went to the beach together.
Caption 21, Francesca e Marika - Il verbo andare coniugazionePlay Caption
For more vocabulary about the beach, check out these videos:
This one is about a beach very close to Pisa, something to keep in mind if you visit Pisa in the summer.
In giro per l'Italia - Pisa e dintorni - Part 3
Finalmente siamo arrivati al mare. [Marina di Pisa]
We've finally arrived at the seaside. [Marina di Pisa]
Caption 1, In giro per l'Italia - Pisa e dintorniPlay Caption
Here's a wonderful series about the Aeolian Islands off the coast of Sicily. They are breathtakingly beautiful and well worth a visit. If you can't visit, watch the videos!
La località isolata e selvaggia di grande bellezza naturale,
The wild and isolated village, with its great natural beauty,
si può raggiungere solo via mare.
is only reachable by sea.
Caption 11, Linea Blu - Le EoliePlay Caption
But let's say you like to swim, but in a pool rather than in the sea.
When you go to a pool regularly, to swim laps, then you can say faccio nuoto (I'm a swimmer, I swim): In the following example, Annamaria Mazzetti trains for Olympic triathlons.
Facciamo nuoto, bici, corsa tutti i giorni.
We swim, cycle, and run every day.
Caption 14, Le Olimpiadi 2012 - Annamaria MazzettiPlay Caption
But let's say you want to go kayaking (andare in canoa), the instructor will ask you:
Do you know how to swim?
Caption 68, Il Commissario Manara - S2EP5 - Mondo sommersoPlay Caption
If not, they will give you a life jacket or life preserver (un salvagente).
But let's say you're at the beach and you just want to go in the water and play in the waves. It sounds strange to us, because many of us have learned that bagno means bathroom...
Noi amici, trascorriamo il tempo giocando,
We friends pass the time playing,
oppure nelle giornate estive facciamo il bagno
or else, on summer days we go swimming
e... invece, in quelle invernali veniamo qui per chiacchierare.
and... and on winter ones we come here to talk.
Captions 16-18, Amiche - sulla spiaggiaPlay Caption
So if someone asks you: "Facciamo il bagno?" you will know they want you to go in the water at the beach or at the pool (in piscina).
Finally, one thing Italians say all the time during the summer is:
Ah, che caldo!
Oh, it's so hot!
Caption 1, Andromeda - in - Storia del gelatoPlay Caption
Caldo is an adjective meaning "hot", but also a noun meaning "heat": il caldo.
Enjoy your summer, or looking forward to summer, depending on where you are.