This modernist 1-drachma commemorative stamp from Greece (Hellas) was issued in 1974 to mark the International Hydrological Decade (IHD), a global UNESCO initiative focused on water research and resource management. The design features flowing abstract water patterns in cool blue tones, contrasted by a bold red sun symbolizing climate influence on hydrology. Its clean geometric style makes it especially attractive to collectors of scientific, environmental, or minimalist thematic issues. A fine addition to environmental philately and modern Greek commemoratives.