Company: TMCWW
Filing Date: 2025-05-21
Form Type: DEFA14A
Source: 0001104659-25-051682
Chunk: 0

Company: TMC the metals Co Inc.
Filing Date: 2025-05-21
Form: DEFA14A
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE14A

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No.)</div>

Filed by the Registrant x

Filed by a Party other than the Registrant
¨

Check the appropriate box:

| ¨ | Preliminary Proxy Statement                                                     |
| ¨ | Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |
| ¨ | Definitive Proxy Statement                                                      |
| x | Definitive Additional Materials                                                 |
| ¨ | Soliciting Material Under §240.14a-12                                           |

<div align='center'>TMC THE METALS COMPANY INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing
Proxy Statement, if other than the Registrant)</div>

Payment of Filing Fee (Check all boxes that apply):

| x | No fee required                                                                                     |
| ¨ | Fee paid previously with preliminary materials                                                      |
| ¨ | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |

<div align='center'>SUPPLEMENT NO. 1 TO PROXY STATEMENT FOR THE ANNUAL AND SPECIAL MEETING OF
SHAREHOLDERS TO BE HELD ON MAY 29, 2025</div>

This proxy statement supplement,
dated May 21, 2025 (this “Supplement”), supplements the definitive proxy statement on Schedule 14A (the “Proxy
Statement”) of TMC the metals company Inc. filed with the Securities and Exchange Commission (“SEC”) on April 18,
2025 and relating to our 2025 annual and special meeting of shareholders to be held in a virtual format on Thursday, May 29, 2025
at 10:00 a.m. EDT (the “Annual Meeting”).

Board Observer Agreement and Other Agreements with First Manhattan Co. LLC

As we previously disclosed,
on May 12, 2025, we entered into a board observer agreement with Zachary A. Wydra, the Chief Executive Officer of First Manhattan
Co. LLC and related entities and portfolio manager of certain accounts managed by First Manhattan Co. LLC, under which Mr. Wydra
will serve as a non-voting observer