The mean height of the sea level off Hook of Holland is 1.2 cm. above datum (N.A.P.), the mean rise of neap tides being 16 cm. and of spring tides 111 cm. above datum. The mean fall of neap tides is to 21 cm. and of spring tides to 63 cm. below datum. L.L.W.S. is 84 cm. below datum.
The average duration of the flood is 6h 47m and of the ebb 5h 38m.
A small intermediate rise not exceeding 6 inches proceeds low water by approximately 2h 22m at practically all spring tides and one third of neap tides, being locally referred to as the Agger.

Tidal constants for ports along the Netherlands coast

	Standard times		Heights		LLWS 1985.0
	H.W. hm	L.W. hm	H.W cm.+NAP	L.W. cm.+NAP	cm.+NAP
Delfzijl	11.05	17.32	135	-164	-207
Harlingen	8.37	16.04	95	-95	-118
Den Helder	6.11	12.56	58	-81	-111
IJmuiden	2.37	10.37	97	-73	-95
Hook of Holland	1.32	7.10	111	-63	-84
Dordrecht	3.07	12.31	86	20	0
Flushing	0.55	7.23	205	-181	-232