Snowmobilers traveling from the United States to Canada should be prepared with the proper legal documentation. 

Current Requirements for Entry Into Canada:

Visas are not required for U.S. citizens entering Canada from the U.S. You will, however, need:

1. Proof of your U.S. citizenship such as your U.S. passport (For information on obtaining a U.S. passport, check with one of the regional passport agencies located throughout the U.S.) or certified copy of your birth certificate issued by the city, county or state in the U.S. where you were born. If you are a naturalized U.S. citizen and do not have a passport, you should travel with your naturalization certificate. A driver's license, voter's registration card or Social Security card is NOT valid proof of citizenship.

 2. Photo identification, such as a current, valid driver's license. All U.S. citizens entering Canada from a third country must have a valid passport. Alien permanent residents of the U.S. must present their Alien Registration Card, commonly called a "Green Card."

If you are a dual U.S./Canadian citizen you should always present yourself as a Canadian citizen when entering Canada. However, U.S. citizens should use their U.S. passports when entering or leaving the United States.  Due to international concern over child abduction, single parents, grandparents, or guardians traveling with children often need proof of custody or notarized letters from the other parent authorizing travel. (This is in addition to proof of citizenship as explained above.) Any person under the age of 18 and traveling alone should carry a letter from his/her parent or guardian authorizing the trip. Travelers without such documentation may experience delays at the port of entry.

To return to the U.S. you will need:
1) Passport or Certified birth certificate    
2) Photo ID

Most passage back to the US is verbal verification but on occasion legal identification may be required.