Hi Lauren,
Thank you so much for the kind words and your question. The basic technique for getting dreamy water is to increase your shutter speed. Depending on your subject, the length of your shutter speed will vary, but usually cool things start to happen around the 1/2" mark.
My usual approach is to target a shutter speed that is long enough to create silky flow in whatever I’m photographing, but short enough that the water doesn’t just turn into mush. For waterfalls I like to count how long it takes water to get from the top of the falls to the bottom, then I’ll start there with my shutter speed. If the falls is super high volume, then I usually end up using a faster shutter speed to preserve some detail.
For the ocean, I have two favorite ways of shooting. The first is to use a shutter speed of around 1". I will find an area with some interesting rocks that the waves are flowing around. Then I wait for a wave to crash, wash up the beach, pause at the top, and just as it starts to recede I’ll trip the shutter. This is how you get the beautiful silky streamers of water.
The other thing I like to do if I’m in an area with bigger waves is use a shutter speed of 1/8" - 1/4". Then I wait till the sun is near the horizon so it shines through the back of the waves, and trip the shutter just as the wave starts to curl. It creates a look almost like stained glass in the wave, beautiful!
For the settings, I start with my ISO at its lowest base setting. For aperture I pick an f-stop that gives me the DOF I need. Then I put my shutter speed at whatever gives me a good histogram. Then I count the number of stops between that shutter speed and my target shutter speed. Sometimes you can get to the target speed just by stopping down your aperture in order to increase your shutter speed a little bit. But if it’s more than a few stops difference between my baseline shutter and targeting shutter, then I use a filter. Usually a 3-stop or 6-stop solid ND.