Exhibit 21

List of Tidewater Inc. Subsidiaries as of December 31, 2020

Name of Subsidiary or Organization

State of Country of Incorporation

Percentage of Voting Securities Owned

1

3291361 Nova Scotia ULC

Canada

100%

2

Al Wasl Marine LLC

Dubai

49%

3

Antilles Marine Service Limited

Trinidad and Tobago

50%

4

Arabia Shipping Limited

Cayman Islands

100%

5

Arrendadora de Naves del Golfo, S.A. de C.V., SOFOM, ENR

Mexico

100%

6

Chalvoyage (M) Sdn. Bhd.

Malaysia

49%

7

Compania Marítima de Magallanes Limitada

Chile

100%

8

Divetide Limited

Thailand

49%

9

DTDW Holdings Limited

Cyprus

40%

10

DTDW Marine Services B.V.

Netherlands

40%

11

Equipo Mara, C.A.

Venezuela

19.90%

12

Global Panama Marine Service, Inc

Panama

100%

13

GM Offshore, Inc.

Delaware

100%

14

GOMI Holdings, Inc.

Delaware

100%

15

Gorgon NewCo, LLC

Delware

100%

16

Gulf Channel Offshore Servicos LDA

Angola

49%

17

Gulf Fleet Abu Dhabi

Abu Dhabi

49%

18

Gulf Fleet Middle East Limited

Cayman Islands

100%

19

Gulf Fleet N.V.

Netherlands Antilles

100%

20

Gulf Fleet Supply Vessels, L.L.C.

Louisiana

100%

21

Gulf Offshore Marine International, S. de R.L.

Panama

100%

22

GulfMark Americas, Inc.

Delaware

100%

23

GulfMark Asia Pte. Ltd.

Singapore

100%

24

GulfMark Capital, LLC

Delaware

100%

25

GulfMark de Mexico, S. de R.L. de C.V.

Mexico

100%

26

GulfMark Foreign Investments LLC

Delaware

100%

27

GulfMark Guernsey International Limited

Guernsey

100%

28

GulfMark Malaysia Inc.

Malaysia

100%

29

GulfMark Malaysia Sdn. Bhd.

Malaysia

49%

30

GulfMark Malta Ltd.

Malta

100%

31

GulfMark Management, Inc.

Delaware

100%

32

GulfMark Marine Trinidad Limited

Trinidad & Tobago

49%

33

GulfMark Maritime S. de R.L. de C.V.

Mexico

100%

34

GulfMark North Sea Limited

United Kingdom

100%

35

GulfMark Oceans, L.P.

Cayman Islands

100%

36

GulfMark Resources, LLC

Delaware

100%

37

GulfMark Servicios de Mexico, S. de R.L. de C.V.

Mexico

49%

38

GulfMark Servicos Maritimos do Brasil Limitada

Brazil

100%

39

GulfMark Shipping, LLC

Delaware

100%

40

GulfMark Thailand, LLC

Delaware

100%

41

GulfMark UK International Limited

United Kingdom

100%

42

Hilliard Oil & Gas, Inc.

Nevada

100%

43

Indigo Fleet Limited

Cayman Islands

100%

44

International Maritime Services, Inc

Cayman Islands

100%

45

Java Boat Corporation

Louisiana

100%

46

Java Boat Corporation B.V.

Netherlands

100%

47

JB Holding Company B.V.

Netherlands

100%

48

Logistica Mexicana del Caribe, S. de R.L. de C.V.

Mexico

100%

49

Mare Alta do Brasil Navegacao Ltda.

Brazil

100%

50

Mashhor Marine Sdn. Bhd.

Brunei

70%

51

Middle East Ships Limited

Cayman Islands

100%

52

Navegadores Servicos de Apoio Maritimo Ltda.

Brazil

100%

53

Naviera Tidex, S. de R.L. de C.V

Mexico

49%

54

Niugini Offshore Services Joint Venture

Papua New Guinea

40%

55

O.I.L. (Nigeria) Limited

Nigeria

82.10%

56

Offshore Labuan Leasing Inc.

Labuan

100%

57

Offshore Marine Inc

Labuan

49%

58

Pacific Tidewater Pty. Ltd.

Australia

100%

59

Pan Marine do Brasil Ltda.

Brazil

100%

60

Pan Marine International Dutch Holdings, L.L.C.

Louisiana

100%

61

Pan Marine International, Inc.

Cayman Islands

100%

62

Pental Insurance Co. Ltd.

Bermuda

100%

63

Point Marine, L.L.C.

Louisiana

100%

64

Purple Fleet Limited

Cayman Islands

100%

65

Quality Shipyards, L.L.C.

Louisiana

100%

66

S.O.P., Inc.

Louisiana

100%

67

SEA Maritime Services Pte. Ltd.

Singapore

100%

68

Semaring Enterprise Sdn. Bhd.

Malaysia

51%

69

Semaring Logistics (M) Sdn. Bhd.

Malaysia

49%

70

Servicios Costa Afuera de Mexico, S. de R.L. de C.V

Mexico

100%

71

Sonatide Marine Services, Ltd.

Cayman Islands

49%

72

Sonatide Marine, Ltd.

Cayman Islands

49%

73

Southern Ocean Services Pte. Ltd.

Singapore

100%

74

Tide States Vessels, L.L.C.

Louisiana

100%

75

Tide States, L.L.C.

Louisiana

100%

76

Tideflo Marine Services Limited

Nigeria

40%

77

Tidewater (India) Private Limited

India

100%

78

Tidewater Al Rushaid Co. Ltd.

Saudi Arabia

50%

79

Tidewater Caribe, C.A.

Venezuela

100%

80

Tidewater Corporate Services, L.L.C

Delaware

100%

81

Tidewater Crewing Guernsey Ltd.

Guernsey

100%

82

Tidewater Crewing Limited

Cayman Islands

100%

83

Tidewater Cyprus Limited

Cyprus

100%

84

Tidewater de Mexico, S. de R.L. de C.V.

Mexico

49%

85

Tidewater Dutch Holdings Cooperatief U.A.

Netherlands

100%

86

Tidewater GOM, Inc.

Louisiana

100%

87

Tidewater GOM Limited

Cayman Islands

100%

88

Tidewater Investment Cooperatief U.A

Netherlands

100%

89

Tidewater Investment SRL

Barbados

100%

90

Tidewater Marine AS

Norway

100%

91

Tidewater Marine Australia Pty Ltd

Australia

100%

92

Tidewater Marine Charter Services Pte. Ltd.

Singapore

100%

93

Tidewater Marine Fleet, L.L.C.

Louisiana

100%

94

Tidewater Marine Gabon S.A.

Gabon

100%

95

Tidewater Marine Hulls, L.L.C.

Louisiana

100%

96

Tidewater Marine Indonesia Limited

Vanuatu

100%

97

Tidewater Marine International Dutch Holdings, L.L.C.

Louisiana

100%

98

Tidewater Marine International Pte. Ltd.

Singapore

100%

99

Tidewater Marine International, Inc.

Cayman Islands

100%

100

Tidewater Marine Sakhalin, L.L.C.

Louisiana

100%

101

Tidewater Marine Service (M) Sdn. Bhd.

Malaysia

100%

102

Tidewater Marine Ships, L.L.C.

Louisiana

100%

103

Tidewater Marine Technical Services (Shenzhen) Co., Ltd

China

100%

104

Tidewater Marine UK Ltd.

United Kingdom

100%

105

Tidewater Marine Vanuatu Limited

Vanuatu

100%

106

Tidewater Marine Vessels, L.L.C.

Louisiana

100%

107

Tidewater Marine West Indies Limited

Bahamas

100%

108

Tidewater Marine Western, L.L.C.

Delaware

100%

109

Tidewater Marine, L.L.C.

Louisiana

100%

110

Tidewater Mexico Holding, L.L.C

Delaware

100%

111

Tidewater Norge AS

Norway

100%

112

Tidewater Offshore Sdn Bhd

Malaysia

49%

113

Tidewater Personnel UK LTD

United Kingdom

100%

114

Tidewater Rederi AS

Norway

100%

115

Tidewater Subsea ROV, L.L.C.

Louisiana

100%

116

Tidewater Subsea, L.L.C.

Louisiana

100%

117

Tidewater Support Services Limited

England

100%

118

Tidewater Venture, Inc

Delaware

100%

119

Tidex Nigeria Limited

Nigeria

60%

120

Troms Offshore Fleet Holding AS

Norway

100%

121

Troms Offshore Management AS

Norway

100%

122

Troms Offshore Supply AS

Norway

100%

123

Twenty Grand (Brazil), L.L.C

Louisiana

100%

124

Twenty Grand Marine Service, L.L.C.

Louisiana

100%

125

Vesselogistics Limited

Cyprus

100%

126

VTG Ships Limited

Cayman Islands

100%

127

VTG Supply Boat Liberia Inc.

Liberia

100%

128

Zapata Gulf Marine L.L.C.

Louisiana

100%

129

Zapata Marine Service (Nigeria) Limited

Nigeria

100%

NOTE: The Company has elected to exclude certain subsidiaries that do not constitute a “Significant Subsidiary” as set forth in Section 601(b)(21) of Regulation S-K.