Agreeing whether a ball is in a hazard

Question
A ball is hit towards a water hazard and almost certainly has gone in it but there is a slight possibility that it might have just missed on the right.  Having looked for the ball where it may have been lucky to land it could not be found so it almost certainly was in the hazard.  My opponent suggested that as there was doubt I would have to take a stoke and distance penalty rather than dropping where the ball crossed the hazard.  I argued that we both knew the ball had gone in the hazard if it was not in the area on the right.  He suggested that as we did not actually see the 'splash' then we could not say the ball was in the hazard.  On this particular hazard you will never see the splash due to the reeds.  Coincidentally my opponent pitched on the left of the hazard and kicked towards it.  He claimed that his ball was in the hazard as we had seen it travelling in that direction.  We obviously saw no splash.  I've rambled on but my question really is about how you deal with a situation where you don't see the ball going in but 'know' that it must have. Thanks

Answer
Dear Martin...thanks for the question.  I had forgotten to set up the vacation time with AllExperts.  In any event, your question is a very interesting one.  Because the game is so much based on honor, this is a very subjective area to deal with. Obviously in a professional tournament, there would be a multitude of means to determine where the ball landed.  Whereas in everyday amateur play, we are left to determine these things ourselves.  If, with reasonable judgement, you determine that the ball must have entered the hazard, you can proceed accordingly.  If there is, again, reasonable evidence that the ball may not have, due to high grass, etc., then a player must consider the ball lost and proceed that way. There is no definitive manner or way to proceed except with your best and honorable judgement.  Always a tough area especially with an opponent's opinion in the mix, but if both players consider the very honor of the game and not personal interests or advantages, the game itself will prevail.  Good luck, thanks again for asking and remember...
Love the game,
skipper