Out of the 8 days we spent in Ibiza, this was my favourite beach.
Secluded, quiet, no screaming children (due to the fact it's a pebble beach presumably), a few locals, nice chiringuito, clear water, comfortable beach beds at a reasonable price.
There were jelly fish, but take your snorkel and avoid them. The snorkelling was so good - we saw a common string ray, and as PADI holders this was quite exciting! There are several rocks you can dive off. No boats.
The chiringuito was great - delicious, fresh fish, cocktails, cold beers.
And then at the top of the beach there is the famous abandoned hotel from 1980s. It's now a graffiti artist's backdrop which makes for an epic walk around. Just be careful of the holes in the floor!