The most likely explanation for the wave that you encountered is a tidally created wave and especially since it was single cresting wave that you could see approaching and continuing past. It sounds just like a bore tide which is similar (sort of) to a tsunami.
It's where one body of water that has a lower level (tide can still be outgoing) meets an incoming body water (flood tide) and creates a wave that progresses to the upper reaches of a bay or arm. Look it up on the internet for a better and more detailed explanation.
One thing to note on the tide chart is the difference in time of peak tides at different locations. The further away from the ocean the later the high tide occurs. This would also be more likely to occur with extreme high and minus low tides.
I'd be willing to bet that if you looked at the tide charts, a map, and noted the time of day that it was on incoming tide. The wave should also be coming in the same direction as an incoming tide but islands and wind direction could have an effect. Somebody with local knowledge would know about this phenomenon if it was a "tidal wave".
