I'd suggest you check out applying the different water materials in the presets to your water plane. Most of those are transparent to varying degrees. There's even once called 'tropical lagoon' or something along those lines. Try them all till you find the one that comes closest to what you want, then tweak that one a bit. The 'lines of light' are done by using a 'gel' on a light source with what's called a 'caustic' pattern. I believe there's at least one somewhere in the texture library inside the materials editor. There are also a number of them available for download, I just can't remember where exactly I got them. I have accumulated about a dozen so far.