UNDATED -- With snow starting to pile up around Minnesota, the DNR is reminding snowmobilers to be use extra caution.

We told you about the dangers of thin ice earlier this week but, DNR Enforcement Education Coordinator Mike Hammer says there are other dangers to be aware of.

Hammer says if you look back on the fatal snowmobile accidents over the years they have three common factors. Those factors are speed, driving under the influence of alcohol and driving too fast at night.

Hammer says remember that anyone born after December 31st, 1976 must take a snowmobile safety course before riding.

According to statistics by the DNR, Minnesota has more than 20,000 miles of groomed trails. More than 18,000 of those are maintained by local clubs.