Coast Guards on both sides of the Canada-U.S. border have warned people against participating in the 2020 Float Down, an annual event that sees thousands of people travel down the St. Clair River on tubes and rafts. 

The event is scheduled to take place this Sunday, Aug. 16 on the river that separates Sarnia, Ont., from Port Huron, Mich.

Ahead of the Float Down, which is more than 30 years old, the Canadian and U.S. Coast Guard Leadership released a joint statement reminding people of the serious legal repercussions that come with crossing the border. 

"This remains an un-sanctioned marine event and poses risks to the participants and other users of the waterways during the 7.5 mile /12 km course. In addition to these risks, the Canada/U.S. border also remains closed until at least August 21, 2020, due to COVID-19," they said.

The RCMP said that any Americans who unintentionally arrive in Canada will be required to wear a mask while being transported back, and will have to complete a COVID-19 health screening.

In 2016, rough conditions led to approximately 1,500 participants requiring assistance when they landed on the Canadian shoreline at Sarnia and Corunna, leaving them stranded, often without identification, money and means of communication. Some had injuries and were suffering from hypothermia.

As well as potential border issues, the Coast Guard's joint statement also warned the event could bring large crowds of people too close together, increasing the risk of spreading COVID-19.

Furthermore, the Coast Guard Leadership warned that "the fast-moving current, large number of participants, lack of lifejackets, alcohol consumption, potentially challenging weather conditions, water temperature, and limited rescue resources" can create difficult emergency response scenarios that can result in serious injuries or fatalities.

In 2014, a 19-year-old, experienced swimmer drowned during the event. A rescue effort was eventually suspended after 21 searches lasting more than 36 hours.