For shooting landscape photos… I simply avoid the hard light period (10AM-4PM). or I use polarized filters to remove the haze and increase the color saturation.
For shooting the people and fish photos… I use flash to partially remove the shadows. (partially compensate the natural light (dead black shadow)) After some practice, you can get a pretty good balance between natural light and flash light… (I know some National Geographic Magazine photographers constantly use flash to create natural looking lighting under the strong hard light condition). Some high-end camera like Canon EOS 1V have build in two exposure meters, one for natural lighting, one for flash. It is very nice and convenient design for these situation. Hope this help.