Exhibit 5.1

Castor Maritime Inc.

223 Christodoulou Chatzipavlou Street

Hawaii Royal Gardens

3036 Limassol, Cyprus

Ladies and Gentlemen:

We have acted as Marshall Islands counsel to Castor Maritime Inc. (the “Company”) in connection with the Company’s registration statement on Form F-3 (File No. 333-254977), as amended by post-effective Amendment No. 1 and post-effective Amendment No. 2 thereto (the “Registration Statement”), as filed with the U.S. Securities and Exchange Commission (the “Commission”), relating to the registration under the U.S. Securities Act of 1933, as amended (the “Securities Act”), of up to $450,000,000 of securities, which may include shares of common stock, par value $0.001 per share, of the Company (the “Common Shares”) (including the related preferred stock purchase rights (the “Preferred Stock Purchase Rights”)), shares of preferred stock, par value $0.001 per share, of the Company (the “Preferred Shares”), debt securities of the Company (the “Debt Securities”), warrants to purchase the Company’s securities (the “Warrants”), purchase contracts to purchase the Company’s securities (the “Purchase Contracts”), rights to purchase the Company’s securities (the “Rights”) and units comprised of any of the foregoing securities (the “Units” and, together with the Common Shares, the Preferred Stock Purchase Rights, the Preferred Shares, the Debt Securities, the Warrants, the Rights and the Purchase Contracts, the “Securities”).

We have examined originals or copies, certified or otherwise identified to our satisfaction, of: (i) the Registration Statement; (ii) the prospectus of the Company included in the Registration Statement (the “Base Prospectus”); (iii) a prospectus supplement thereto dated May 23, 2023 (the “Prospectus Supplement”) (iv) the Stockholders Rights Agreement dated as of November 20, 2017 by and between the Company and American Stock Transfer & Trust Company, LLC (the “Rights Agreement”); and (v) such corporate documents and records of the Company and such other instruments, certificates and documents as we have deemed necessary or appropriate as a basis for the opinions hereinafter expressed. In such examinations, we have assumed the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as copies or drafts of documents to be executed, the genuineness of all signatures and the legal competence or capacity of persons or entities to complete the execution of documents. As to various questions of fact that are material to the opinions hereinafter expressed, we have relied upon statements or certificates of public officials, directors of the Company and others.

Based upon and subject to the foregoing, and having regard to such other legal considerations which we deem relevant, we are of the opinion that under the laws of the Republic of the Marshall Islands:

This opinion is limited to the laws of the Republic of the Marshall Islands as in effect on the date hereof and we express no opinion as to any other laws, rules or regulations.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement, and to each reference to us and the discussions of advice provided by us under the headings “Legal Matters” in the Prospectus Supplement, without admitting we are “experts” within the meaning of the Securities Act or the rules and regulations of the Commission promulgated thereunder with respect to any part of the Registration Statement.