Natural trap for sea monsters.

I'm writing a setting including a fishing village specialized for the capture and processing of large sea creatures. The basic idea being that sailors chase the creature into a bay that's easy to get into but has no easy way out, so it can be harpooned and set upon by the villagers.

My initial thought was a kind of rocky ledge right under the water with an incline on the outer side, with a fairly shallow area on the inside to avoid letting the creature gain enough speed to get over the ledge.

Anyone see any obvious problems with this?

How about using the tide?

Coral Reefs for certain areas. Rock formations, caves.

Perhaps the sailors make the monster(s) chase them to shallow waters, where their mobility goes through the window and they become sitting ducks, like a bleached whale.

Beached Whale*

A bleached whale would have very little pigment.

Who's say it couldn't be both?

Ah very true. Very true indeed.

Depends on how smart this "Sea Monster" is. Fishermen around the world routinely catch fish by herding them into and enclosed area with a very small entry/outlet. Fish cant remember where the exit is, so they just swim around.

How big is this thing? Would it be practical to close off the bay with a big, reinforced net? What about a water gate?

Poisoned bait is always a possibility.

Again, consider simply exploiting the tide. The difference between high and low tide can be huge, enough so that a "killing pit" dug into the bay might be perfectly accessible from the ocean at high tide and totally cut off at low. It's then just a matter of keeping the big beastie in the danger zone for a few hours, until it's too late for escape.

Don't necessarily even need to do that much; a tidal current could be strong enough to prevent the beastie from swimming back out against it if it's flowing through a relatively narrow opening.

Bear in mind that the opening needs to be big enough to get the monster in but too small for the monster to get out.

The tides trick fixes this issue but it also means you've got one chance every 12 hours.

Wow, didn't expect this to get so many replies. Everything here is great; I'll keep it all in mind while I figure out whether or not this world has a tide.

Depending on whether or not this world has magic, you might also consider a magically (or even seasonally) induced tsunami.

Step 1: Trick sea monster into range.

Step 2: Let it get sucked up by the Tsunami.

Step 3: Tsunami washes over an artificial reef designed for this purpose, slightly above water level but rather deep on the 'shore' side, so that it's functionally a land bridge between the sea and a deep pit/lake when there's nothing happening.

Step 4: Sea monster 'falls' into the pit/lake and can't get out for the same reason whales can't crawl back - Square-Cube Law is a huge bitch, and they're sea monsters with an 'S' Underwater terrain rating and 'D' in Land/Sky/Space.

Step 5: Stabbity time.

Step 6: Food and profit.

Step 7: Clean-up and repeat as necessary.

I would call it the Red Bay, on account of how much blood is spilled there.

Tidal wave, Deus, Tsunamis are triggered by underwater landslides and earthquakes and tend to wreck cities.

Here it is for anyone who cares. http://caiel.deviantart.com/art/Red-bay-499279111