How would you feel about volunteering during your next cruise vacation? Several cruise lines offer programs to help you find that feel-good sweet spot where you're having fun on your trip, while also taking a bit of time to pitch in to aid the people, animals and conservation efforts in ports that need it most. Voluntourism, a longtime travel industry niche, has risen in popularity in recent years as a way for travelers to give back and make a difference in the communities they visit. The effort has increasingly spread to cruises, where itineraries offer charitable initiatives onboard and excursions with an eye toward volunteering in port (like helping to build schools, teaching English to local schoolchildren or cleaning up beaches). If you are looking to add a few good deeds to your next voyage, there are a wide variety of ways to partake in cruise-based voluntourism -- even if you don't want to dedicate your whole vacation to that purpose. Here are some of the latest philanthropic offerings from ship to shore.