It's like a zoo but the animal are not caged. Giraffes, monkeys, hippopotamus, even lions and tigers wander around freely. Perhaps you may think, what if these animals attack? No, they won't, because you look at them from inside your car or bus. Here, it is the difference. At the zoo, the animals are locked in the cage. At the Safari Park you are the ones locked inside your vehicle.   "... even lions and trigers wander around freely" (line 2) The underlined word means ...