Thirdly and more to the point even the Himalayas were under water, the fossil hunters will vouch for that.
If we take the Himalayas as mountains they were never underwater. The rocks that they are made of were. The fossils, in fact, show that they were not underwater as the mountains they are now.
If you think that the fossils show that the
mountaints were underwater then I would be very interesting in the facts that you start with (include them all) and the reasoning you follow from them to arrive at such a conclusion.