Recently I have come across with the problem of the penetration ability of various kinds of wave and would like seek advice here. 1. Gamma ray has higher energy (higher frequency) as compared with x-ray and therefore gamma ray is considered to have higher penetration ability than x-ray. 2. For various kinds of hydrographic surveys for checking (a) the seabed profile (multi-beam echo sounder), and (b) the ground conditions under seabed (seismic profiler). It appears that the lower the frequency, the higher the penetration ability. It seems to me that both (1) and (2) above are true, but their behavior in terms of penetration ability is totally different. Is there something wrong in (1) and (2); or is there some consideration/factor that I have missed. Thanks alot.