Could mass minelaying submarines close British waters?

Could a mass German force of minelaying submarines close British waters?

It would create serious work, but Britain's established minesweeping and patrol capacity would expand earlier and limit the strategic effect.

Minelaying submarines could be dangerous, but Britain already treated mines as a major threat and maintained a large force of minesweeping trawlers. Those vessels could work from ports for shorter periods than submarines had to remain at sea, easing crew and logistics demands. The attacker must lay mines across a broad area, whereas the defender needs to clear only a usable channel through it. Because Britain could expand an existing response sooner, mass deployment would create serious work without guaranteeing that British waters stayed closed.