Dynamic Water FPS swimming prototype class

public class DW_Swimming : MonoBehaviour {
    public float SwimSpeed = 2f;

    private bool _isSubmerged = true;
    private IDynamicWaterFluidVolume _water;

    private void OnTriggerEnter(Collider otherCollider)
    {
        // Making sure the object we have entered is DynamicWater
        if (otherCollider.CompareTag(FluidVolume.DynamicWaterTagName))
        {
            _water = otherCollider.gameObject.GetComponent<DynamicWater>();
        }
    }

    private void OnTriggerExit(Collider otherCollider)
    {
        // Making sure the object we have left is DynamicWater
        if (_water != null && otherCollider.CompareTag(FluidVolume.DynamicWaterTagName) &&
            otherCollider == _water.Collider)
        {
            _water = null;
        }
    }

    private void Update() {
        // If we are in the water
        if (_water != null)
        {
            // If we are actually submerged to a some extent
            float waterLevel = _water.GetWaterLevel(transform.position.x, transform.position.z);

            float min = collider.bounds.center.y;
            float max = collider.bounds.center.y + collider.bounds.size.y / 2f;

            // Assume we can swim when at least half submerged into water
            _isSubmerged = (min < waterLevel && max > waterLevel) || (min < waterLevel && max < waterLevel);
            // Value of 1 means fully submerged, value of 0 means not submerged
            float submergedCoeff = Mathf.Clamp01((waterLevel - min) / (max - min));

            if (_isSubmerged) {
                // Swim up
                if (Input.GetKey("z")) {
                    transform.Translate(Vector3.up * SwimSpeed * submergedCoeff * Time.deltaTime);
                }

                // Swim down
                if (Input.GetKey("x"))
                    transform.Translate(-Vector3.up * SwimSpeed * submergedCoeff * Time.deltaTime);
            }
        }
    }
}