large waves
瀾 centers on large, surging waves, emphasizing their size and power.
瀾 combines 氵 (water) with 闌, which likely contributes the sound ラン and may carry a sense of surging or overflowing.
The water radical 氵 beside 闌 suggests water that is not calm but surging. Picture a gate (門) holding back a flood of water that bursts through as large waves.
For ラン, imagine a large wave running toward the shore: run -> ラン, and the wave crashes with power.