Light: Daily activities may include city walking tours, visits to sites, game drives on bumpy roads, or easy hikes.

Light/Moderate: Daily activities may include city walking tours, visits to sites, game drives, or easy hikes, with options for more physical activities such as hiking, kayaking, snorkeling and biking.

Light or Moderate: Travelers can choose between a light or moderate activity level. For a light level of activity, daily activities may include city walking tours, visits to sites, game drives on bumpy roads, or easy hikes. For a moderate level, travelers should be prepared for multiple hours of physical activity (e.g. hiking, kayaking, biking) each day.

Moderate: Travelers should be physically fit and prepared for multiple hours of activity (e.g. hiking, kayaking, biking) each day.

Moderate/Strenuous: Travelers should be physically fit and prepared for multiple hours of activity (e.g. hiking, kayaking, biking) each day. Certain days may have more challenging physical activity, such as ascents/descents on steep mountainous terrain.

Strenuous: Designed for experienced active travelers in excellent physical condition, these itineraries may include full-day hikes (sometimes at high altitude) or full-day kayaking excursions. Trails often include steep ascents/descents on mountainous terrain, with some exposed sections.

Maximum: The ultimate challenge for serious hikers who are very fit and have experience hiking or trekking at high elevations. These itineraries include numerous challenging, full-day hikes.

26 Beautiful Travel Photos of 2016

Nat Geo Travel editors picked their favorite travel photos published in 2016. See majestic images from around the world that struck our experts.