Actually, a 2.5 knot current is significant. To swim against it for any length of time and to any depth is quite strenuous.
I have to ask... Did the dive boat deploy the divers up-current so that you could do the dive with the flow of current..? or... did the dive boat deploy the divers down current so that you had to swim against the current during the dive?
Did you descend along a buoy line or did you "free fall" the discent?
Just curious....