Tom Brady -- SURVIVES KAYAK OF DOOM

Here's Tom Brady casually paddling away in a kayak over the weekend ... and GIVING ALL OF BOSTON A FRIGGIN' HEART ATTACK!!!

Before you accuse us of sensationalizing the situation, consider this fact -- back in 2009, Brady had to be RESCUED from the Charles River after falling out of his Kayak while goofing around with some friends.

After the rescue, Brady thanked the woman who fished him out of the water ... telling her, "You saved my life."

Despite the risks -- and with NFL opening day less than 2 weeks away -- Brady got back into the Charles River with his wife Gisele and son Ben on Saturday.

Fortunately, everyone emerged from the water healthy and happy.

Meanwhile, it's the Jets who seem to be drowning these days ...