Okeanis Eco Tankers Corp. – Nissos Sifnos Update

ATHENS, GREECE, July 30, 2026 - Okeanis Eco Tankers Corp. (the “Company” or “OET”) (NYSE:ECO / OSE:OET), today provides an update on one of the Company’s Suezmax tankers, the Nissos Sifnos. In the early morning of 30 July, 2026, while the vessel had called for loading Kazakh origin crude at the Caspian Pipeline Consortium (CPC) terminal, was hit by a drone.

All our crew is safe and unharmed. The incident did not cause any spill or other pollution from the vessel, which only sustained minor damages and is continuing its voyage operations.

Contacts

Company:

Iraklis Sbarounis, CFO Tel: +30 210 480 4200

ir@okeanisecotankers.com

Investor Relations / Media Contact:

Nicolas Bornozis, President Capital Link, Inc.

230 Park Avenue, Suite 1540, New York, N.Y. 10169 Tel: +1 (212) 661-7566

okeanisecotankers@capitallink.com

About OET

OET is a leading international tanker company providing seaborne transportation of crude oil and refined products. The Company was incorporated on April 30, 2018 under the laws of the Republic of the Marshall Islands and is listed on Oslo Stock Exchange under the symbol OET and the New York Stock Exchange under the symbol ECO. The sailing fleet consists of ten modern scrubber-fitted Suezmax tankers and eight modern scrubber-fitted VLCC tankers.

Forward Looking Statements This communication contains “forward-looking statements”, including as defined under U.S. federal securities laws. Forward-looking statements provide the Company’s current expectations or forecasts of future events. Forward-looking statements include statements about the Company’s expectations, beliefs, plans, objectives, intentions, assumptions and other statements that are not historical facts or that are not present facts or conditions. Words or phrases such as “anticipate,” “believe,” “continue,” “estimate,” “expect,” “hope,” “intend,” “may,” “ongoing,” “plan,” “potential,” “predict,” “project,” “should,” “will” or similar words or phrases, or the negatives of those words or phrases, may identify forward-looking statements, but the absence of these words does not necessarily mean that a statement is not forward-looking. Forward-looking statements are subject to known and unknown risks and uncertainties and are based on potentially inaccurate assumptions that could cause actual results to differ materially from those expected or implied by the forward-looking statements. The Company’s actual results could differ materially from those anticipated in forward-looking statements for many reasons, including as described in the Company’s filings with the U.S. Securities and Exchange Commission (the “SEC”). Accordingly, you should not unduly rely on these forward-looking statements, which speak only as of the date of this communication. Factors that could cause actual results to differ materially include, but are not limited to, the Company’s operating or financial results; the Company’s liquidity, including its ability to service its indebtedness; competitive factors in the market in which the Company operates; shipping industry trends, including charter rates, vessel values and factors affecting vessel supply and demand; future, pending or recent acquisitions and dispositions, business strategy, areas of possible expansion or contraction, and expected capital spending or operating expenses; risks associated with operations; broader market impacts arising from war (or threatened war) or international hostilities; risks associated with pandemics, including effects on demand for oil and other products transported by tankers and the transportation thereof; and other factors listed from time to time in the Company’s filings with the SEC. Except to the extent required by law, the Company expressly disclaims any obligations or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in the Company’s expectations with respect thereto or any change in events, conditions, or circumstances on which any statement is based. You should, however, review the factors and risks the Company describes in the reports it files and furnishes from time to time with the SEC, which can be obtained free of charge on the SEC’s website at www.sec.gov.

This information is subject to the disclosure requirements pursuant to Section 5-12 of the Norwegian Securities Trading Act.