Change now the layer's Blending Mode on Multiply and make the Opacity smaller, till 74 %.

fantasy art

Insert on a new layer the picture having clouds on it:

fantasy art

This
layer must be processed also, choosing the layer's mask and the Gradient Tool.

fantasy art

Get back to the sea cost's layer to create a mask out of this layer. Select after that another type of Gradient Tool to make the layer invisible:

fantasy art