Study aim: The overall goal of this study is to compare the effect of Swedish massage with and without hydrotherapy on pain intensity, knee range of motion, muscle strength, quality of life, and physical ability in individuals with knee osteoarthritis. Design: A randomized, double-blind, controlled clinical trial with parallel groups using Randimizer.org for randomization. The study will have three groups, each consisting of 30 participants. Settings and conduct: This research will be conducted at the Karaj Branch of Islamic Azad University, and the university's pool and equipment will be used for hydrotherapy procedures. In this study, blinding will be double-blind, such that both participants and outcome assessors will be unaware of the type of intervention and group allocation. The intervention will be implemented by a team separate from the evaluation team. Participants/Inclusion and exclusion criteria: Subjects will be 90 women aged 45 to 60. Inclusion criteria: Having knee pain of at least three out of ten on a visual analog pain scale, diagnosed with knee osteoarthritis with a grade of three on the Kellgren & Lawrence grading system (in all three groups). Exclusion criteria: Having any contraindications to hydrotherapy such as kidney disorders, use of non-steroidal anti-inflammatory drugs. Intervention groups: The first intervention group will receive Swedish massage for 8 weeks, 3 sessions per week for 45 minutes. The second intervention group will receive hydrotherapy exercises in addition to Swedish massage. The third group will not receive any intervention and will be the control group. Main outcome variables: Assessment of pain intensity using the visual analog scale, active range of motion of the knee joint, assessment of quadriceps muscle strength, Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire for quality of life assessment, 6-minute walk test.