Company that was established by the partners in the Yam Tethys project to receive a transmission license from the Mari production platform located offshore Ashkelon via a pipeline directly to Ashdod. Yam Tethys laid a 42 km pipeline from the production platform to the receiving terminal in Ashdod with the work completed at the end of 2003, with a capacity for up to 6 bcm per annum.

Partners in the company include Noble Energy (47.058%), Delek Drilling 25.5%), Avner (23%) and Delek Investment (4.441%). Yam Tethys has two proven reserves, the Noa reserve and the Mari reserve.

The total Yam Tethys contracts include: a contract signed with IEC in June 2002 for 18 bcm of gas which started to flow in February 2004 at $2.47 mmbtu; a contract with Oil Refineries signed in September 2004 with supplies started to flow in November 2005 for 1.3 bcm at $2.50 mmbtu; a contract signed in July 2005 with the Hader Paper Plant for 0.43 bcm of gas which started to flow in August 2007 at $2.50 mmbtu; a contract with the Delek IPP in Ashkelon signed in August 2005 and with supplies that started to flow in August 2007 to supply 1.8 bcm at $2.4 mmbtu; a spot contract signed in August 2006 with IEC at a price of above $5 mmbtu; a contract signed in March 2008 with IC which started to flow in October 2009 to supply a total of 2 bcm at $3.50 – $4.50 (oil linked price with floor & ceiling) and a contract signed on 23 July 2009 with IEC to supply 5 bcm of gas over 5 years at the flat price of $1 billion leading to a price of $5.45 mmbtu.

On 24th December, IEC signed a LOI with the Yam Tethys partners (Mari and Noa partners) according to which the parties would carry out negotiations. As part of a separate LOI, IEC expects to purchase natural gas from the Company and its partners to establish a strategic inventory reserve at Mari-B. The Mari-B partners would provide IEC with injection, storage and withdrawal capabilities for this inventory under a related service. On 24th December another LOI was signed between the partners in the Yam Tethys project and those in the Tamar project, according to which the strategic reserves of gas would be provided by the Tamar project, subordinate to the partners in both projects agreeing. The LOIs are not yet binding. IEC board of directors has ordered for the negotiations to conclude with a binding GSA within up to 6 months.

In March 2010, Yam Tethys stated that they are revising upward the estimated volume of gas at the Mary B drilling site. The new estimate is 7.5% higher than earlier estimates. Netherland, Sewell & Associates Inc., a Texas-based independent petroleum consultant, increased its estimate of the quantity of natural gas in the well by 1.89 billion cubic meters (66.7 billion cubic feet) to 27.52 billion cubic meters. The amount is about 1.9 billion cubic meters, valued at an estimated $340 million. The estimated value was based on the average price for the gas at Mary B in existing deals, namely $5 per million BTUs. NSAI estimates that the proved updated reserves of natural gas on the 31/12/09 are about 13.38 bcm and proved and probable of about 14 bcm.