This study evaluates whether a brief, structured team reflection programme embedded within routine elite underwater rugby training is associated with longitudinal change in key psychosocial team over 6 weeks and assessed at baseline (T0), mid-intervention (week 3; T1) and post-intervention (week 6; T2). Outcomes include team cohesion, psychological safety, peer trust and team identification measured via validated questionnaires.

A standardised set of short reflection components is embedded into the squad's training microcycle over 6 weeks. Sessions occur twice weekly immediately post-training (before athletes 15 minutes. The protocol includes 16 sessions distributed across five components (internal-state check-in, specific recognition, structured micro-reflection on team functioning, collective identity reinforcement, and one controlled vulnerability session), all implemented under a strict "share-only" rule to preserve psychological safety (no interruptions, cross-talk, evaluation or rebuttal). Facilitation is shared between a staff member and a rotating athlete leader. Fidelity and dose are monitored via a brief session log (delivery, minutes, facilitator, attendance, prompt completion, adherence to share-only rule). Objective sport performance outcomes are not collected; training availability and injury/illness status are recorded descriptively to contextualise exposure.

Inclusion Criteria:

• Male elite underwater rugby athletes aged 18 years or older.
• Officially rostered in the squad and training regularly (minimum 2 sessions per week).
• Able to complete Spanish-language questionnaires.
• Willing to participate and provide written informed consent.
• Available to complete assessments at baseline (T0), week 3 (T1), and week 6 (T2).

Exclusion Criteria:

• Unable to complete the questionnaires reliably (e.g., language/comprehension barriers).
• Anticipated prolonged absence during the 6-week period that would prevent meaningful exposure to the intervention and/or completion of follow-up assessments.
• Declines participation or does not provide informed consent.

Individual participant data (IPD) will not be shared publicly. The sample is small and drawn from a single, identifiable elite underwater rugby squad, so even de-identified records could carry a meaningful risk of re-identification when combined with contextual information (e.g., roster composition, training attendance patterns, and time-point assessments). Participant consent covers analysis and publication of aggregated results rather than unrestricted public release of participant-level data. Summary statistics and full methodological details will be reported in publications. De-identified extracts or additional details may be considered on a case-by-case basis, subject to a data-use agreement, ethics approval, and safeguards that minimise re-identification risk.