TDW Tidewater Inc

Filed Pursuant to Rule 424(b)(3)

Registration Statement No. 333-228029

Prospectus Supplement No. 3

to Prospectus dated March 4, 2019

Tidewater Inc.

3,434,934 Shares of Common Stock

Issuable upon the Exercise of Outstanding GLF Warrants

This Prospectus Supplement No. 3 (the “prospectus supplement”) updates, amends and supplements the prospectus dated March 4, 2019 (the “Prospectus”), as amended and supplemented by the Prospectus Supplement No. 1 dated May 10, 2019 and the Prospectus Supplement No. 2 dated August 13, 2019, which forms a part of our Registration Statement on Form S-1 (Registration No. 333-228029), as amended. Capitalized terms used in this prospectus supplement and not otherwise defined herein have the meanings specified in the Prospectus.

This prospectus supplement updates, amends and supplements the information included in the Prospectus with information contained in our Current Report on Form 8-K, filed with the Securities and Exchange Commission on September 4, 2019, which is set forth below.

This prospectus supplement is not complete without the Prospectus, as amended and supplemented. This prospectus supplement should be read in conjunction with the Prospectus, as amended and supplemented, which is to be delivered with this prospectus supplement, and is qualified by reference thereto, except to the extent that the information in this prospectus supplement updates or supersedes the information contained in the Prospectus, including any amendments and supplements thereto. Please keep this prospectus supplement with your Prospectus for future reference.

Our Common Stock is listed on the NYSE under the symbol “TDW.” On September 4, 2019, the last reported closing sale price of our Common Stock on the NYSE was $15.52.

Holding shares of our Common Stock involves risks that are described in the “Risk Factors” section beginning on page 4 of the Prospectus and “Risk Factors” in the documents incorporated by reference therein.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is September 4, 2019

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 3, 2019

(b), (c), (d), and (e) On September 3, 2019, Tidewater Inc. (“Tidewater”) announced that John T. Rynd, President, Chief Executive Officer, and a director of Tidewater, is retiring and resigning from all positions with Tidewater effective immediately (the “Transition Date”).

The board of directors of Tidewater (the “Board”) has appointed Quintin V. Kneen, who currently serves as Executive Vice President and Chief Financial Officer of Tidewater, to succeed Mr. Rynd as President, Chief Executive Officer, and a director of Tidewater, effective as of the Transition Date.

The Board intends to conduct a search for a new chief financial officer to succeed Mr. Kneen, who will continue to serve in that role until a successor is appointed.

Mr. Kneen, age 54, has served as Executive Vice President and Chief Financial Officer of Tidewater since immediately following Tidewater’s November 2018 business combination with GulfMark Offshore, Inc. (“GulfMark”). From June 2013 until the consummation of the business combination, Mr. Kneen served as President and Chief Executive Officer of GulfMark. Mr. Kneen first joined GulfMark in June 2008 as Vice President – Finance, was promoted to Senior Vice President – Finance and Administration in December 2008, and served as Executive Vice President and Chief Financial Officer from 2009 until his promotion to President and CEO in 2013. Prior to joining GulfMark, Mr. Kneen was Vice President – Finance & Investor Relations for Grant Prideco, Inc., serving in executive finance positions at Grant Prideco between 2003 and 2008. Earlier in his career, Mr. Kneen held executive finance positions at Azurix Corp. and was an Audit Manager with the Houston office of Price Waterhouse LLP. He holds a Master of Business Administration from Rice University and a Bachelor of Business Administration in Accounting from Texas A&M University, and is a Certified Public Accountant and a Chartered Financial Analyst.

In connection with this appointment, the compensation committee of the Board has approved the following adjustments to Mr. Kneen’s compensation arrangements, each effective as of the Transition Date: (1) an increase in annual base salary to $500,000, (2) an increase in his target short-term incentive opportunity to 100% of base salary, and (3) an increase in the severance multiple that would apply to him upon certain actual or constructive terminations within a two-year protected period following a change of control (as defined in Tidewater’s standard change of control agreement) to two times annual base salary plus target bonus. These changes will be memorialized in amendments (the “Amendments”) to Mr. Kneen’s existing employment agreement or change of control agreement, as applicable, each of which has been previously filed with the SEC. The foregoing description of the Amendments does not purport to be complete and is qualified in its entirety by reference to the full text of the Amendments, which Tidewater expects to file as exhibits to its Quarterly Report on Form 10-Q for the quarter ended September 30, 2019.

With respect to Mr. Rynd, as a result of his departure, he will be entitled to receive certain previously-disclosed payments and benefits due to him upon a termination of employment without cause under his employment agreement dated February 15, 2018, a copy of which has been previously filed with the SEC (the “Rynd Agreement”). The Rynd Agreement also requires Mr. Rynd to comply with certain restrictive covenants following his termination of employment, including an agreement to not disclose confidential information and, for a two-year period following the Transition Date, non-competition and non-solicitation agreements.

1