2 Answers

Tools > Options > Content tab > check mark "Block pop up windows" to turn the blocker on.

To turn off the blocker for a webpage, On your browser click Tools > Options > Content tab > next to "Block pop up windows", see Exceptions, click it. Paste or type address of site you want pop ups to be allowed for, click Allow  

Having done most of my own diving around Vancouver, dark and murky water was largely the norm and, given that my dive computer did not have an active backlight, I found that I commonly used my dive watch to have a quick look at link my elapsed time. My dive computer could be charged with a light, but it link lasted only a couple of minutes whereas most any decent dive watch would be glowing link from the surface swim alone.