l = 4; w = 1; h = 2; aquarium = Graphics3D[ {Line[{{0,0,0},{w,0,0},{w,0,h},{0,0,h},{0,0,0}, {0,l,0},{w,l,0},{w,l,h},{0,l,h},{0,l,0}}], Line[{{0,0,h},{0,l,h}}], Line[{{w,0,0},{w,l,0}}], Line[{{w,0,h},{w,l,h}}]} ];
In[6]:=
Show[aquarium];
Up to Aquarium