Due to the nature of the development of gas transmission network, the problem of ensuring reliability and safety of the underwater gas pipelines was practically exhausted by the calculation of underwater crossings through the rivers, lakes, and other water barriers. However, in recent years in connection with the development of oil and gas fields on the shelf, and the globalization of the gas transmission network, the question came up related to designing, building, and subsequently ensuring the stable operation of the offshore deep-water pipelines. Individual information about the accident rate of the offshore pipelines is given. They mainly concern the coastal pipelines transporting raw materials from the offshore production platforms to the onshore terminal. The largest number of accidents is typical for the pipelines of small diameters (2–6 inches) — 59 % of their total number. A group of medium-diameter pipelines (8–16 inches) accounts for 32 % of accidents. Pipelines of large diameter (18–36 inches) are the least susceptible to damage — about 3 % of accidents. In recent decades, the offshore main gas pipelines were widely used and are considered as the most promising way of transporting gas due to higher reliability, safety, and environmental friendliness, as well as the advantages of direct Analysis is presented in the article concerning the accident rate and features of failures of the offshore gas pipelines. The criteria of limit states and the algorithm for calculating the stress-strain state of the offshore pipeline, which are the main part of the safety assessment, are given. Methodology for the safety of the offshore gas pipelines was developed, based on which the example of the safety assessment of the Blue Stream gas pipeline is given. The materials of the article were used in the development of the projects for the offshore gas pipelines and are also included in the industry regulatory document.