Both hammock and bivy has advantages and disadvantages regarding on the certain situation. The hammock has the benefit that it can be brought wherever. You can hang it up on trees, poles, etc. Additionally, you can bring it with you while having a camp trip or simply going to the beach for sunbathing. Some people prefer to get hammock than sleeping on the ground. Meanwhile, bivy is lightweight and better than a tarp. It will fully cover you and also completed with an insect protection. This is because a bivy sack is spacious than the sleeping bag. Moreover, it fits in shelters for extra warm as well as protection from bugs or rain.