With so many animal species endangered these days, there are opportunities all over the world to aid research and to rescue animals in need.
Instead of spending your leisure time lounging on the beach, you could help save bottlenose dolphins and other marine mammals in the western Mediterranean. A program in the Ligurian Sea employs volunteers to track and study the animals to learn how to better protect them in a designated cetacean sanctuary. An itinerary in Kenya offers volunteers 11 days of rehabilitating mangrove ecosystems -- a task that bolsters the local fish population and aids the people who depend on those fish for food. If you prefer a seaside destination, numerous programs focus on improving the survival chances of sea turtles on beaches around the globe.
Programs like these benefit from the help of retirees who have the maturity to understand that wild animals, though they need our help, are not cuddly pets. Be sure to think carefully about your comfort zone in terms of accommodations and hands-on work with animals before you commit to a program.