Kostrena – 1.10.2023

This weekend it was time to go scuba diving in Kostrena again. The weather was still nice and sunny. Due to strong winds a few days earlier the water temperature decreased by several degrees but was still around 20°C.

We did two dives, both being over an hour long (69 and 71 minutes). Maximum depth is about 37 m if you stick to the wall. The entry is from the shore where you have a plateau that goes down slowly to about 12 m. At 12 m is a cliff that goes to about 37 m in depth but that isn’t constant. The bottom goes even further down but you would need to move away from the wall.

The visibility was fairly good with the exception of a few spots.

Overall we saw quite a lot but it was again quite different from the last time. Most memorable were a few large schools of fish that didn’t mind me at all. All of a sudden a large school came from above the wall and around me. Another one was a large common dentex (Dentex dentex). They are normally quite shy but this one didn’t really care for us so we got a chance to observe it swimming just a few meters away for quite some time.

As I am not really equipped to make videos, especially wide-angle ones, I simply waited and observed.


Two of the common species of anemone that I see are the golden anemone (Condylactis aurantiaca) (left) and the fat anemone (Cribrinopsis crassa) (right).

Condylactis aurantiaca Cribrinopsis crassa

Can you spot a few shrimps in the golden anemone? I counted three. They are a bit out of focus, unfortunately.

Hint: One is at the left edge about in the middle and two are at the bottom edge on the left half.


This time I was lucky as I saw a new species for me and one that I hadn’t seen in a while.

First a few nice pictures of a Cratena peregrina. Not only that, but the top two include a bonus Flabellina ischitana as well. There were a few more around. If you look closely at the top two pictures, I think that the curly white strands could be the egg masses of the Cratena peregrina or some other nudibranch.

Cratena peregrina Cratena peregrina Cratena peregrina Cratena peregrina

Next is a trio of Peltodoris atromaculata in their natural habitat which is the stony sponge (Petrosia ficiformis). That is their main and preferred food.

Peltodoris atromaculata

And the last of the nudibranchs is a first for me, the Berghia coerulescens. If you look at the pictures they often have the cerata in a more blue color. Even so, it was quite nice to see one.

Berghia coerulescens Berghia coerulescens

Feather stars

The feather stars (Antedon mediterranea) come in various color combinations. They are always a nice sight, especially when there are a lot of them grouped in one place.

I managed to see two nice examples, one in yellow and another in red and white color combination.

Antedon mediterranea Antedon mediterranea

Other organisms

The largest scorpion fish in the Mediterranean Sea is the red scorpionfish (Scorpaena scrofa). This one was around 40 cm in length by my estimation. In the picture, it doesn’t look that large though.

Scorpaena scrofa

Its smaller cousin is the small red scorpionfish (Scorpaena notata). This one was a bit annoyed by me I think, estimating from its behavior. While it was fun to look at I left it alone after a few moments to not disturb it too much.

Scorpaena notata Scorpaena notata

And for the end, the only European spiny lobster (Palinurus elephas) I was able to find there. Unfortunately, I didn’t see the large lobster I saw on my previous dives. I can only hope it is still in that area.

Palinurus elephas


Another great day was spent scuba diving. It’s always fascinating how the same location can change so quickly in terms of animals in just a matter of weeks. There are normally large schools of fish there but there is always something different.

I am sure I will be back soon.