data=ExampleData[{"Statistics","OldFaithful"}];
𝒟=KernelMixtureDistribution[data,"StandardGaussian"];

rng=RandomVariate[𝒟,500];

Show[SmoothDensityHistogram[rng,ColorFunction->"TemperatureMap",Mesh->Automatic],ListPlot[FindClusters[rng,2],PlotRange->{{1,6},{30,110}},PlotStyle->{Black,Red}]]

Show[
SmoothHistogram3D[rng,
PlotStyle->Opacity[0.5],PlotLabel->Text[Style["Duration vs. Waiting Time",FontFamily->"Helvetica"]],MeshStyle->Opacity[.3],ColorFunction->"TemperatureMap",Boxed->False,ViewPoint->{2,-2,1},ImageSize->Medium],
Graphics3D[
MapThread[
{#2,Point[Table[Append[pt,0],{pt,#1}]]}&,{FindClusters[rng,2],{Black,Red}}
]
]
]