| The human female reproductive cycle is also approximately circalunar, according to a 28-day rhythm of spring and neap tides. |
| The water is evened out all over the earth's oceans, producing neap tides. |
| On neap tides it's usually slack enough to dive an hour before this and up to an hour after. |
| So we have spring tides regularly once a fortnight, with neap tides in between. |
| At neap tides the rock shows only a few black teeth with sea-weed gums above the surface. |
| They are much more likely to be found tucked into the lee of the wreck, only spreading out at slack water and on neap tides. |
