You may not give much thought to it when splashing around in the bath or going for a swim - but realistically simulating water is an incredibly difficult task for computers.
A new simulation from PhysX however appears to be very close to nailing it.
These videos show some incredibly impressive - and beautiful - effects complete with waves, spray, space constraints and even some imaginary tank-shattering bullets.
The technology is the result of some very complicated algorithms called 'Position Based Fluids' (PDF) combined with some powerful computing ability.
Essentially PDF reduces the water to a large number of small particles, each of them subject to a set of rules.
These mimic the properties of water such as surface tension, incompressibility, and the decreasing energy in a wave as it slowly dies out.
What's most impressive is the way in which the 'water' interacts with its surroundings.
Objects such as rabbits and werewolves (the obvious choices) and bullets fired at simulated glass tanks demonstrate the capability of the system to handle changes in the environment.
It can even show what happens when energy is transferred back into the system like a wave machine (a process called vorticity confinement).
The mathematical properties of fluid mechanics is called the 'Navier–Stokes existence and smoothness' and is still a relatively misunderstood area.
It is one of the so-called 'Millennium Prize Problems', one of seven whose complete and correct solution to will bag the person behind it a $1 million reward.