Here's a few pics of some under-ice beaver trapping.
Here's an active bank den. Viewing from across the stream. Notice the feed pile and bubble trail between the feed pile and shoreline.
Another view from standing on top the den:
Here's a feeder den located about 100 yards upstream. Notice peeled sticks near the entrance. These are often much easier to set as they are typically shallower than main dens or lodge entrances:
Pic of a 45-pounder in a 330. Check out that cute face looking through the ice:
Beaver shown in previous pic. Always use dead sticks to stabilize the traps. Beavers will stop and chew the stakes if green: