Imagine a tiny fish climbing a waterfall like a mountaineer. It may sound impossible, but in Hawaii, a special fish called the waterfall-climbing goby does exactly that. These small fish, usually less than 20 cm long, scale steep waterfalls that can reach heights of nearly 300 metres.

The reason lies in their unique life cycle. Goby eggs hatch in freshwater streams, but their larvae drift into the ocean to grow. Later, the young fish must travel back upstream to freshwater to survive and reproduce. To reach these safe habitats, they climb waterfalls that many animals would never attempt.

Their bodies are specially designed for this challenge. Gobies have a pelvic suction cup formed from their fins that helps them stick to slippery rocks. Some species even use their mouth as a second sucker, allowing them to slowly crawl upward.

Despite the dangerous journey, the few that succeed help maintain healthy freshwater ecosystems in mountain streams.