No one likes a candle that they can't light, so here's a quick tip on how to fix a tunneled candle!
Common cause for a tunneled candle
An example of what a tunneled candle looks like
Quick fix for a tunneling candle
A tunneled candle is no one’s friend, and even I tunnel them here + there. But no, they aren’t ruined + yes, you can save them!
A common cause for a tunneled candle is not letting it burn long enough, which is understandable because who lives their lives around the melt pool needs of their candles? (That’s a partial joke... sometimes I do this, but that’s not normal behavior lol)

Tunneling happens when the wax around the outer edges of the jar doesn't melt at the same time as the wax around the wick of your candle.
A quick fix: trim your wick (step one for every candle interaction ever. please, just always trim your wick), take a bit of aluminum foil, fold it in half (think hotdog style), then wrap it around the edge of your candle. Make a little scarf for your jar, leaving the center open for the flame. Then light your candle + in a bit, you should have a good-as-new candle!
Be careful taking the aluminum foil off... it was just next to a live flame so it’ll be hot, but you’re smart people + you knew that already ☺️
Of course, if it’s tunneled beyond saving, that’s another story. You can always pop that candle on a warmer to use it up, but the reason why this foil method won’t work for a super tunneled candle is that the wick will be lower than the highest point of the newly melted wax. (Think like a rock on the beach — when the tide comes, the rock gets covered right? Same thing here!)
It’s about to be brutally cold + snowy, so staying home/lighting all the candles is about to be a new personality trait for those of us in wintery states for the next 6 months, so I hope this helps if you need it some day!