2 guides, each rated 1 to 5 with the reason — and two lists per place, where you are comfortable and where to pay attention. Nowhere is called dangerous; the specific thing is what helps.
The wildlife is genuinely wild and the rules exist because people have died ignoring them: stay in the vehicle unless your guide says otherwise, never walk between tents after dark without an escort, and zip the tent. Malaria is the real medical risk and prophylaxis is strongly advised. Crime is not a meaningful concern inside the parks.
Comfortable: Serengeti National Park · Arusha
Leaving the vehicle anywhere in the park
Walking to your tent at night without the guard, in an unfenced camp
Ngorongoro Crater — the crater rim road in fog, which is where the accidents are
Generally safe but Zanzibar is conservative and predominantly Muslim — cover shoulders and knees away from beach resorts, and swimwear stays on the beach. Malaria prophylaxis is advised; use repellent at dusk. Yellow fever certificate may be required depending on your route.
Comfortable: Stone Town · Nungwi · Kendwa · Matemwe
Stone Town — the alleys after dark
Nungwi — the beach at night
Dressing as if on a resort beach when you are not — Zanzibar is conservative and Muslim-majority
The tide on the east coast, which goes out a kilometre and comes back fast
The ratings are this site's own, from the guides' authors and the corrections readers send in; they are not an index. Read the general advice in travel safety tips.