Very dangerous infact as the vast majority of merchant ships were totally unarmed with almost no defense against enemy subs, ships and planes at all. Alot of them were loaded with gasoline and ammunition and when they got hit with a torpedo they were often blown to bits before they knew what hit them.
My Dad spent 5 years in the Navy and for the most part his job was escorting the merchant ship convoys across the ocean to Great Britain and North Africa and doing their best to keep the Germans away from them. Sonar was very basic back in those days and it was often difficult for them to locate submarines until it was too late. Dad saw many ships & crews blown up close by and he often talked about what a horrible feeling it was seeing so many men killed and not being able to do alot to help them. One night Dad saw 3 ships go up within a few minutes of each other very close to his ship.
As soon as a ship was hit they'd try to figure where the subs were and start dropping depth charges (underwater bombs) and firing hedgehogs (a type of rocket) but they'd never really know if they got the subs or not and they'd usually just sink to the bottom when the hulls were fractured. They figured they got a few of them as they'd see oil slicks and debris come up but that was also a ploy of the Germans, to release oil and shoot debris out torpedo tubes to make it look like they'd been hit.
It was a terrible time for everyone during the war, Navy, Army, Air Force and Merchant Marine but they did what they were asked to do and they won the fight and allowed those of us that followed to live the lives we do today and we owe them more than we can ever imagine.
And lets never forget Canada's military was totally volunteer and nobody was forced to go to war as in some other countries.
My Dad's brother served 5 years in the Army, my Mom's brother was a bomber pilot and was killed along with his crew when their plane went down, an uncle served in the British Army and spent 3 years in a Japanese prison camp in Burma and the stories he told of the constant torture would make you nearly puke.
My Dads father was in the British Army in WWI and fought as a sniper in the trenches of France and in his own words said he killed "far too many men but it was what had to be done". He survived even after being hit with shrapnel and was awarded the Military Medal for heroism.
I was lucky and most of those men survived to live long and wonderful lives and even my Grandfather didn't die until I was 35 years old.
I tell these same stories every year at this time as I am VERY VERY proud of what the men in my family did when they were needed.
That's my Dad on your right covered in coal dust as he just finished stoking the engine room boilers and had just come up for some fresh air.
Dad's ship....HMCS Kitchener