If you have sinus trouble would scuba diving be harmful?

Diving with sinus congestion can be extremely harmful. As you descend, you must "equalize" your ears otherwise a "squeeze" occurs. This "squeeze," as divers call it, happens when there is an air pocket of lower pressure in the sinus cavity or by the ears and higher pressure around it. It causes extreme pain and may rupture an ear drum, if you try to get through it. PADI - the diving certification organization - advises strongly against diving with sinus trouble, even if controlled by decongestants.