There are a few other options:
1.) EZ-Water: Heat the beads to melt them than pour the liquid into your base.
You might need to build walls to contain the "Water" till it is set.
Can be resoftened by using a gas-torch ( to eliminate bubbles) and than shaped or carved, etc.
Drawback, it will always have a slight yellow colouring.
Hint:
Don't try to paint the "water" won't work, you will need to paint the base for the appr. colour and than pour the water over it. Also helps achieve a depth effect.
Most Model Railroad stores will carry it and it is fairly cheap.
2.) Clear acrylics: Variety of stuff out there, mix and pour like above.
Advantage less to no heat generation and thus less change of warping the base. You know the stuff they make for clear amulets/paperweights/etc with stuff "floating" in them. Fiberclass supply store should have it.
3.) Clear Resins: Like above, but generates more heat and easily traps air-bubbles in it.
All of the above will seldom try 100% with no discolouration, but allow you to pour it in layers(might be visible from side).
Over here got a similar product to EZ-Water that tries 100% clear and also is available in blue and green with colour stick to adjust the colour.
It comes in like a jelly block, used it once and worked well.
Problem: VERY EXPENSIVE.
Forgot also check the local arts supply store, they might have a product that will also dry clear.
Hope this helps.