Praia da Marinha, Portugal

Water clarity averages 15 meters, allowing visitors to count fish from the clifftop; underwater, 40 species of colorful wrasses and bream thrive in seagrass meadows. As a European destination, it undercuts tropical rivals by 50% on lodging: nearby hotels average $100 per night versus $600 in French Polynesia. The iconic double sea arch, known as the Algar de Benagil's smaller sibling, is a selfie magnet but retains a quieter feel with only 500 beachgoers on summer afternoons. This balance of geological drama and European affordability makes it a top pick for nature lovers who skip the tropics.