You might want to look a little bit more into this ‘tumbling’/destabilization, it might indicate you and your kit are way out of balance. It sounds like your buddy was not getting tumbled so perhaps discuss the experience with him and understand why he is more stable than you underwater. This compounded what was going on with current. Getting your kit sorted will make the unexpected things much easier to deal with.
Beyond that, I’d recommend what others here like GDog have mentioned, getting heavy (dump gas) getting close to the bottom and crabbing across current as opposed to swimming into it, you can learn a technique called pull and glide often used in cave diving but it can be somewhat helpful in these situations. Additionally if you find yourself at a site without structure, looking at the bottom for geoduck holes as a place to get enough leverage to move across current using modified pull and glide technique without having to use a tool can be useful. Of course a trowel as Fritz mentions is a better alternative to a knife in general for this purpose, more leverage and less likely to break/accidentally stab a creature in the sediment, but i tend to not like extra stuff in my hands when dealing with situations that need extra attention to buoyancy and also extra attention to resources like gas - a tank can be hoovered down in a flash when actually working underwater.
Unless you are absolutely getting wholloped in a downwelling and you absolutely can’t make your way across the current flow up the slope and the only option is to bail, I don’t recommend ascending up into the water column unless you can see that it is obviously slower ‘up there’ as the current is most often a bit slower close to the bottom as the friction of the water/sediment slow it down. I have not really found slower water in the water column to be the case here in the northwest unless you are out on some big wrecks where the sills cause some intersting current movement, things like slack on the bottom and rip snorting current on the way down, this changes when you go to different environments such as caves, rivers and big wrecks and things where learning from someone who knows the water movement of a specific dive is key (sometimes the flow is slow on the ceiling, etc.. sometimes you can use the current for transportation on a wreck, hiding in current shadows for swim one direction and then drifting the length of the wreck in the other, wash/rinse/repeat)
And of course as folks have said, learn your sites. There are two sites that i find a bit notorious for these situations (redondo and les Davis) that have some pretty intense river assisted currents at certain tide changes not really covered in NW shore dives etc. The river water is piled up by the incoming tide and then upon reversal, boom, the current gets a river assist and can surprise even the strongest divers. Often finding a way to hunker down and or slowly make your way across these “rivers” works well because it is a transient phenomenon and once the piled up water has unloaded from the river delta things will return to ‘normal’ for the prediction. Basically right out of openwater one, “stop, think, breathe, act”
Other sites have this to a lesser degree if you are interested in the phenomenon, you can periodically see the ulva flowing ‘downhill’ and ‘uphill’ at cove 2, its never overwhelming but for sure different than the normal slow moving to no moving currents in that back eddy.
In addition to the longshore currents that Yelloweye mentions, there are also topographic current nuances... Alki point (the clay walls off the actual point), can have massive down/upwellings, Don armeni boat launch in the turbidity channel/fault line, north of mee-kwa-mooks as well just to name a few. These are influence by the bathymetry/bottom contours and how the currents hit them when coming around points and stuff. All fascinating, and all kind of predictable once you know what to look for. For a primer you can go to the Pacific Science Center and take a looksie at the tidal model which is a scale replica of the basin and you can see the movement clearly with dye injection.
A great primer for all this (albeit a bit dry) can be seen here as well:
Another interesting read/resource is Curtis Ebbesmeyer’s book “Flotsametrics and the Floating World: How One Man’s Obsession With Runaway Sneakers and Rubber Ducks Revolutionized Ocean Science,”. A bunch of it is about big ocean currents but there is a bit about his early career studying the blobs of water that move around Puget Sound and hood canal that are quite interesting.
Final note to echo what Yelloweye mentions about drifting on surface being better than running out of gas on the bottom... You are pretty much in a bathtub. A BIG bathtub but when you surface there will always be land in sight assuming you are diving in the Sound. It may feel scary but you CAN swim to shore from almost any site in south/mid sound, it may take time but you are not in the middle of the ocean. Swim to shore, you may need to hitch a ride back to your car, it may be embarrassing, but its way better than compounding a bit of an adventure into a potentially life threatening out of gas emergency for you and your buddy.
Disclaimer: i have not actually taught a dive class in a decade or so, but have in the past and don’t think this stuff has changed
I was at Three Tree North yesterday and got caught in highly undesirable current during flood tide. at 60-80ft, the current was minimal but as we ascended to ~30ft, all of a sudden I got caught in current where I ended up getting rolled around. No matter what I did, I couldn't stay prone. I tried drifting with the current (but still got tumbled), tried swimming into the current (couldn't keep that up). my buddy let me latch onto him (but I ended up tumbling him, too) until things settled down. Any advice on what to do the next time?