Underwater exploration is a fascinating activity because of the richness of sea life, the beautiful colors, and the contrast with terrestrial life. It can be done by diving or snorkeling -today there is fine equipment for diving and taking underwater pictures- and, apart from being a source of pleasure, it forms the basis of modern ecological and behavioral marine studies. Diving is an emotional activity. The silence of the submarine world, only interrupted by breathing, has more than once evoked the monsters of the fabulous tales of my youth. Maybe because, although much time has elapsed since then, I still have a youth's ability to evaluate everything for the fascination it conveys. However, no more than that can be gained from underwater watehing. I am not saying that this is destined to be a futile exercise. Picasso watched sea urchins much in the same way while revealing their quintessence in his paintings at the Castle of Antibes. What I mean is that today marine life can also be viewed from the perspective of the natural products involved. This knowledge, subsequent to Picasso's time, adds much to the overall picture.