Hunting for relics can be pretty tedious, but it can also reveal new areas of the world that you never knew existed. I have found about 60 relics (enough for the achievement) and stopped after that point. Relics are a tad bit harder to find than lost letters or memory cards but you should have no trouble finding a relic in under 3 minutes or so if you follow a few basic guidelines. First off, look around you. Is the relic on a highpoint in the map, or are you lower to the ground? If you find yourself highly elevated, the relic may be on a steep hill or in a large cave inside that hill. It's now your job to circle around the vicinity of the relic and search for it up high or down low. If you find yourself lower to the ground, search for small cave entrances or bodies of water. Relics will often be hidden in hard to reach, underwater areas. I hope this helped, good luck with your relic hunting!