The answer is yes, but. I have an undermount sink in cherry butcherblock. The bottom of the butcherblock was sealed with a zillion layers of waterlox. Ikea sells a membrane or something to go under their bb over a dw. I just sealed it really well. The top of my bb, I treat with mineral oil beeswax. Waterlox is a polymerized tung oil and tung oil is derived from nuts and I didn't want to have a potential problem w/ nut allergies. You can buy prepared mineral oil beeswax or make your own. I make my own and use it on both the bb and my soapstone counters.

That was the 'yes' portion of the answer. The 'but' is that you need to be diligent about wiping up when you're done with the sink. I've seen posters answer to this question that they just ripped out there horrible looking dark splotched, moldy mess of a counter/sink and posters answer that there counter/sink looks as good as the day it was put in. You would never allow pools of water to sit on your dining room table day in and day out because it would ruin the finish. The same goes for your sink area. Using the mineral oil beeswax, water beads up great, but I still wouldn't let it just sit there without wiping it up. HTH.

I don't have a BB countertop. I agree with Laxsupermom but I wanted to add that it also depends on the type of wood you use. Something like Teak and Ipe which are very dense woods are do better near water even if you are not super diligent about wiping it up!

Good luck!

There is also a marine version of waterlox which a lot of people use around the sink cutout.

You all are so helpful. Thank you forty times over. The marine version waterlox is a super idea.