The main attraction here is the huge grotto of Neptune (https://grottadinettuno.it/en/). Tickets can be purchased in advance or on the spot, in the case of online tickets, you must arrive 40 minutes or more before the time of the visit.
There are 654 steps leading up and down to the grotto. We had planned to visit it, even with a small child, but it turned out that on the day of our visit the grotto had closed early. After looking at the steps, we were not too upset :)
At the very edge of the cape there is a lighthouse and a weather station, but the road is closed.
On the cape there are two equipped observation decks. One near the entrance to the steps to the grotto.
Second is here 40.574220, 8.159117.
If you go up the slope from the second viewpoint
Then, here 40.570599, 8.158065, you will find a small grotto, from which you can take interesting pictures.
Getting there: The easiest option is to arrive by car. Go here 40.563387, 8.163254 and look for a vacant spot along the road. The second option is to come by boat from Alghero, then you don't have to go up the stairs. The third option is to take a bus from via Catalogna in Alghero, click here for the timetable https://grottadinettuno.it/en/come-arrivare/.