-[ prismic △ sanctum ]-

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Move yourself behind them. When you are directly behind them, hook your arm around their neck with your elbow at their throat. Then swim with your legs and the other arm. They will naturally float and you can haul in someone who is substantially larger than you are.

As far as the current goes, try to swim diagonally to the curent until you get near the water's edge. River currents are less strong around the sides of the river, so from there you'd have an easier time getting up to the shoreline.