Can anyone help me with the following problem?

I have a number of positions in longitudinal and latitude positions.
At these positions I have data about the tide.(Water heights to be
exact.)
I want to plot these heights in a 3D surface in excel, but the grid is
irregular.
I have tried to set up a regular grid, but then the grid gets too
tight and the clarity gets appalling..
Perhaps it is possible to plot the values of the water height in
another program such as Google Earth?

If anyone has a solution, thanks in advance,

Peter