to rise high (of water); to overflow; to swell
to be filled with (emotion, energy, etc.); to be bursting with; to be brimming with; to pervade (of an atmosphere, feeling, etc.); to prevail
春の川が雪解け水でみなぎる。
The spring river overflows with snowmelt.
若さとエネルギーがみなぎっている。
Brimming with youth and energy.
自信がみなぎる表情で登壇した。
I took the stage with a face brimming with confidence.