No. “Jal‑samādhi” (ending one’s life by drowning) is not allowed in Jain Dharma.

• It is violence (himsa) toward oneself. Jainism forbids every form of intentional injury, including self‑harm.
• Jain scriptures only allow Sallekhanā (Santhara) in rare, disciplined conditions—gradual fasting with complete peace of mind, non‑attachment, and under guidance. It is undertaken when death is near (e.g., incurable illness, extreme old age) and must be free from passion, fear, or despair.
• Any sudden or forceful method—drowning, jumping, poisoning, cutting, burning, etc.—is classified as suicide driven by passions, and is condemned by both Śvetāmbara and Digambara traditions.
• Sallekhanā is about purifying intentions and gently letting go; “Jal‑samādhi” is a violent act that binds harmful karmas.

In short: Only Sallekhanā, done correctly and rarely, is permitted. Jal‑samādhi is not.