I often find air turbulence to be the worst over big masses of water, whether it be over the Atlantic or Pacific. I will look at my glass of water (or other beverage) to see if it is spilling over and if it is about to, I will try and finish drinking it so it won't create a mess over my lap. Otherwise I try to recline my seat back and just try to relax the best as I can as I know eventually it will pass, although even 5 minutes of heavy turbulence can seem like forever.