Climbers moving from inland crags to sea cliffs consistently find routes harder than the grade suggests. The additional difficulty is environmental rather than technical, and it is real.
The tide sets a hard time limit
Many sea cliff routes start from a ledge or platform that is only accessible for part of the tidal cycle, which turns the climb into a timed exercise.
A party moving slower than planned may find the base submerged, removing the option of descending the way they came.
Planning therefore begins with a tide table rather than a guidebook, and the usable window is often shorter than the time the route nominally takes.
Retreat is frequently the hard direction
Inland, abandoning a route usually means descending to easy ground. On a sea cliff the ground below may be water, and the only way out is upward.
This changes the decision-making entirely, because committing to a route can mean committing to finishing it regardless of how it is going.
Some routes are approached by abseiling in from the top, which makes retreat effectively impossible once the rope is pulled.
Salt and moisture degrade the rock
Sea air accelerates weathering, and rock that is solid inland can be friable near the water, particularly in the zone regularly wetted by spray.
Holds break more often, and fixed protection corrodes rapidly, so anything found in place on a sea cliff is treated as decoration rather than as gear.
Damp and greasy rock in the lower sections is common even on dry days, since spray and humidity keep the base of a cliff wet.
Birds and seasonal restrictions apply
Sea cliffs are primary nesting habitat, and access is restricted during breeding seasons on many coastlines, with the dates set locally and enforced by agreement or by law.
These restrictions change from year to year as colonies move, so current local information matters more than a printed guidebook.
Climbing during a closure risks the access arrangement for everyone, which is why the restrictions are generally observed strictly within the climbing community.
What this means for choosing a route
Dropping a grade or two below the usual comfortable level is standard advice for a first sea cliff, and it reflects experience rather than caution for its own sake.
Going with someone who knows the crag is worth more here than almost anywhere else, because the approach, the tide and the escape options are rarely obvious from below.
Anyone unfamiliar with this terrain should climb with qualified local instruction first, since the consequences of a routine mistake are considerably higher than they are inland.