CheckWaterLevel()

static EWaterLevels CheckWaterLevel ( DayZPlayer pPlayer, out vector waterLevel )

static

if total water depth >= 1.5m && character is 1.5m in water

См. определение в файле DayZPlayerUtils.c строка 425

    {
        SHumanCommandSwimSettings swimData = pPlayer.GetDayZPlayerType().CommandSwimSettingsW();
        vector    pp = pPlayer.PhysicsGetPositionWS();
        waterLevel = HumanCommandSwim.WaterLevelCheck(pPlayer, pp);
        
        if (waterLevel[1] < swimData.m_fToCrouchLevel)
        {
            return EWaterLevels.LEVEL_LOW;
        }
        else if (waterLevel[1] >= swimData.m_fToCrouchLevel && waterLevel[1] < swimData.m_fToErectLevel)
        {
            return EWaterLevels.LEVEL_CROUCH;
        }
        else// if (waterLevel[1] >= swimData.m_fToErectLevel)
        {
            float waterLevelToSwim = swimData.m_fWaterLevelIn;
            if (PlayerBase.Cast(pPlayer).IsClimbingLadder())
                waterLevelToSwim += 0.2;
            
            if (waterLevel[0] >= swimData.m_fWaterLevelIn && waterLevel[1] >= waterLevelToSwim)
            {
                return EWaterLevels.LEVEL_SWIM_START;
            }
            else
            {
                return EWaterLevels.LEVEL_ERECT;
            }
        }
    }

Перекрестные ссылки HumanCommandSwim(), SHumanCommandSwimSettings::m_fToCrouchLevel, SHumanCommandSwimSettings::m_fToErectLevel и SHumanCommandSwimSettings::m_fWaterLevelIn.