1 Easy:
No or little physical requirements. May include short walks, sailing, sightseeing by bus, or helicopter rides.

2 Moderate:
No hard physical requirements. May include various terrain walks.

3 Demanding:
Physically demanding. May include walking or dogsled riding in various and/or steep mountainous terrain.

4 Strenuous:
Highly demanding activities, requiring good physical condition and endurance. May involve extremely low temperature, rough terrain, etc.