The Denver Crossing

What you're actually crossing

Between Denver Sluice and Salters Lode lies a short stretch of the tidal Ouse — mudbanks, moving water, and normally one crossing window a day. It's the hinge of the whole system: everything between the Middle Level and our river passes through it. Treat it with respect and it's routine; turn up unannounced and you may be admiring the mud for six hours.

When the window opens

The keepers work it from the predicted tide height at King's Lynn:

• Neap tides (under 6 m at King's Lynn): the window opens around an hour before high water. On neaps they can lock either side of high water — in on the flood as soon as there's depth, carrying on into the ebb — so these are the long, forgiving windows.
• Spring tides (over 6 m): crossings run on the ebb, roughly two hours after high water — nearer three on the biggest tides.
• The smallest neaps: sometimes there simply isn't enough water, and there's no crossing that day. Silt building up outside the sluice moves the goalposts too.

Those timings are the keepers' summer rule of thumb — in winter, ring them or work from the King's Lynn tide tables.

How to plan it

One habit covers everything: ring well in advance on 01366 382013 and talk your trip through. Tell them your boat, your draught and where you're heading — knowing who's coming lets the keepers plan the locking order and get everyone through the window. Boats over 60 feet must also warn Salters Lode ahead of time: on some tides a long boat can't make the turn, and certain days rule out the transit entirely.

Entering the lock on the flood and on the ebb are different manoeuvres — know which you're getting, and you'll come alongside without touching the tyres. Paul the lock keeper scores every entrance; aim for a quiet nod.

Beyond the crossing

Denver is also the gateway to bigger water: the New Bedford River (the 100ft) runs tidal and dead straight to Earith as a shortcut past the whole Ely loop — read the tidal advice note and clear it with the Hermitage or Denver keepers first — and the tidal Ouse continues seaward to King's Lynn and the Wash for the genuinely adventurous.