Electro-optical and laser systems are presently deployed in naval operations around the world. The performance of these systems is negatively affected by optical turbulence in the atmosphere, quantified by the parameter Cn2. The strength of the integrated optical turbulence Cn2 was investigated for several coastal locations in different climatic conditions: False Bay (South Africa), the Baltic Sea (Bay of Eckernförde, Germany), the Mediterranean Sea (Crete, Greece), the Gulf of Mexico (Dauphin Island, Alabama, US), and the Arabian Gulf. The over-water, near-surface turbulence was characterized along paths that typically spanned 1.5 - 8.7 km using large aperture scintillometers. The dependency of Cn2 on the air-sea surface temperature difference and wind speed is discussed, and the results for the five geographic regions are compared and discussed in terms of environmental conditions and climate.