Shipping History 110 Merchant marine 53 Commerce 48 Harbors 43 Security measures 40 Prevention 27 more ... Maritime Economics 21 Economic aspects 20 Navigation 16 History, Naval 14 Maritime law 14 Sailors 14 Business logistics 13 Government policy 13 Transportation 12 Foreign relations 11 Container ships 10 Law and legislation 10 Piracy 10 Safety measures 10 Terrorism 10 Maritime terrorism 9 National security 9 Ports of entry 9 Economic conditions 8 Freight and freightage 8 Hijacking of ships 8 Rates 8 Taxation 8 less ...