Cala Mitjana is a nice beach east of Cala Galdana. Again, you can take the coast path to walk there. It was a bit more than 30 min. from the beach at Cala Galdana to Cala Mitjana, with additional 15 min. detour to a viewpoint with a great view on the bay. The sandy beach was nice, quite some people but not so filled like at Cala Macarella, and there's even a toilet (though not that well maintained). But I was missing some trees that offer shadow, it quickly got hot when the sun came, although it was a pretty cloudy day. The water again was crystal clear and snorkelling was nice, we even saw a skate which I've never seen before in the wild.
Cala Macarella is a lovely beach west of Cala Galdana. You can take the coast path from Cala Galdana, which took us about 40 min. On the way, there are three viewpoints which are worth a detour (about 10 min. each) as the view on the coast is fantastic! From the last viewpoint, you already can see the Cala Macarelleta, the smaller one of the beaches. Before you reach Cala Macarella, you need to go 213 steps down to the beach. It's a sandy beach, very nice, but many people. There's a beach bar, and there are some pine trees which offer shadow. The water was crystal clear, perfect for snorkelling. We saw many fishes, especially at the rocks at the eastern part of the bay where you also have some little caves. We really like it there!
In Cala Galdana, the river Torrent d'Algendar flows into the sea, and you can follow that river into a gorge called Barranco de Algendar. After you leave the street, you'll reach a gate and in the bushes at the left side is a small wall with steps. We weren't sure if it it's allowed to go there, but others did it also and why would you offer such a possibility if you don't want to have people walk there? Then we followed the path to the right, and after a short time there was another gate, and again some steps to climb over it. The gorge is pretty wide there, but with high rocks, I liked it there! It's calm (compared to the busy beach!), and we only met several sheep and very few other people, some with binoculars. After about an hour walk, we reached a fence where we didn't see any possibility to go further, so had to turn. But it was a nice place there, with the high rocks directly next to you, and a cove which was occupied by sheep!
There's a bus station opposite the Hotel Cala Galdana and another one up the main street to Ferreries. There are direct connections to Mahon and Ciuatadella, but not too many. You can find the schedule at the bus station, and it also had the schedule for the return journey. You also can go to Ferreries and take busses from there which may offer more options.
We did take the bus to Ciutadella, which was 2,85€ (single) and took about 30 min. We only stopped at the second stop up in Cala Galdana and somewhere in Ciutadella before we reached the main stop in Ciutadella. The bus number somehow was a different than we expected (48 instead of 52), but in the front screen there was a sign that showed it travelled between Cala Galdana and Ciutadella.
The bus was pretty comfortable and air-conditioned, and many people used it. It seems they were mainly British as they did queue up so nicely at the bus stop in Cala Galdadna! On the return journey, the bus was so full that the remaining people were not allowed in, but the next bus came just 10 min. later. Our bus had an additional stop in Ferreries which the later one did not have, so that both busses reached the bus stop in Cala Galdana at the same time.