In general it is easier to dig under the ground near rivers............there are probably caves anyways, and the ground, walls, etc are wet.....making them easier to break.............u are not going to blast near the falls anyways.........it is a nat. park in both Brazil and Argentina.........................so u can dig........under and up.........to the falls........use any natural caves......just knock down wall by wall.............until u get to what u are searching for........