Functioning, as described in the International Classification of Functioning, Disability and Health (ICF), increasingly raises interest in the world of child rehabilitation, especially because its application empowers patients and parents by not putting the emphasis on disability in terms of the medical diagnosis but on the person’s lived experience and the level of functioning that might be achieved. However, this requires the correct understanding and application of the ICF framework to overcome differences in the often locally used models or the understanding of disability, including mental aspects. To evaluate the level of accurate use and understanding of the ICF, a survey was performed on studies of aquatic activities in children aged 6–12 with developmental delay published between the years 2010 and 2020. In the evaluation, 92 articles were found that matched the initial keywords (aquatic activities and children with developmental delay). Surprisingly, 81 articles were excluded for not referring to the ICF model at all. The evaluation was performed by methodological critical reading according to the ICF reporting criteria. The conclusion of this review is that despite the rising awareness in the field of AA, the ICF is used inaccurately and often not according to the model’s biopsychosocial principles. For the ICF to become a guiding tool in evaluations and goal-setting for aquatic activity, the level of knowledge and understanding of the framework and language needs to be increased via curricula and studies on the effect of interventions on children with developmental delay. Even more so, the level of understanding on how to apply functioning among instructors and researchers working in the aquatic environment needs to be increased.