That's more or less it, as far as I understand. There's the hexagonal lattice of solid water ice, where hydrogen bonds form a 3D tetrahedral structure which is

That's more or less it, as far as I understand. There's the hexagonal lattice of solid water ice, where hydrogen bonds form a 3D tetrahedral structure which is very stable. At the boundary, there are no molecules "above" the solid latice, so those water molecules are held less tightly. The exact dynamics are challenging to predict because we can't exactly see what's going on (most simulation based).