I have found a small island near an underwater monument.
I cannot mine on that island almost at all because I keep getting hit with Mining Fatigue even though I am underground with many solid blocks of dirt, stone and sand between me and the guardians. The Wiki suggests that you should be safe from the guardians ray if there are solid blocks between you.
Comments 4
yes, you are safe from their ray, but however, the mining fatigue has nothing to do with their ray; it's a special attack for the elder guardians. You will have to kill all 3 elder guardians in the temple to get rid of the mining fatigue effect.
http://minecraft.gamepedia.com/Elder_Guardian#Behavior
Once each minute, the Elder Guardian will search for players in a 50-block radius who are not afflicted with Mining Fatigue, who are afflicted with a level of fatigue lower than III, or whose affliction will wear off in less than one minute. The players found will be inflicted with Mining Fatigue III for 5 minutes, and a ghostly image of the Elder appears to the player.
Intentional.