Actually, the interesting thing about this dive is not that my diving partner was an Ertzaintza rescue diver with more than 4,000 dives but that, at a certain point, he put me in a compromise, since one of the basic rules of diving is that you should not separate yourself from your diving partner and you should be aware of him so, when he decided to go on his own into a small cave that we didn't know previosuly, I had to make a decision.
As you can see in the video I ended up following him after thinking about it for a few seconds at the entrance of the cave, being aware that getting into a cave that you don't know can be dangerous but, of course, you can't leave him alone inside, just in case something happens.
As you can see in the video, the one that goes second finds the cave without visibility due to the mud that raises the flapping if you're not careful and it's something that can overwhelm you a bit, especially if you're not an experienced diver; one of the most fundamental rules underwater is: always remain calm and not panic.
Even so the cave was small and shaped like a siphon it's something you don't know until you are inside and that implies assuming a certain level of risk, thing that usually is not recommended underwater.
Fortunately, everything went well and I didn't have to rescue the Ertzaintza's rescue diver (it would have been weird, right?), although I'm also a rescue diver myself but not at his level or with his experience.
Video recorded with a GoPro Hero 4 Adventure.