Aquaphobia or waterfright is a persistent and abnormal fear of water. Aquaphobia is a specific phobia that involves a level of fear that is beyond the patient's control or that may interfere with daily life. People suffer aquaphobia in many ways and may experience it even though they realize the water in an ocean, a river, or even a bathtub poses no imminent threat. They may avoid such activities as boating and swimming, or they may avoid swimming in the deep ocean despite having mastered basic swimming skills. This anxiety commonly extends to getting wet or splashed with water when it is unexpected, or being pushed or thrown into a body of water.

Of the simple phobias, aquaphobia is among the more common subtypes. In an article on anxiety disorders, Lindal and Stefansson suggest that aquaphobia may affect as many as 1.8% of the general Icelandic population, or roughly one in fifty people.

Most phobias are classified into three categories and, according to the "Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition" (DSM-V), such phobias are considered to be sub-types of anxiety disorder. The categories are:

1. Specific phobias: Fear of particular objects or social situations that immediately results in anxiety and can sometimes lead to panic attacks. Specific phobia may be further subdivided into five categories: animal type, natural environment type, situational type, blood-injection-injury type, and other.

2. Agoraphobia: a generalized fear of leaving home or a small familiar 'safe' area, and of possible panic attacks that might follow. It may also be caused by various specific phobias such as fear of open spaces, social embarrassment (social agoraphobia), fear of contamination (fear of germs, possibly complicated by obsessive-compulsive disorder) or PTSD (post traumatic stress disorder) related to a trauma that occurred out of doors.

3. Social phobia, also known as social anxiety disorder, is when the situation is feared as the person is worried about others judging them.

Phobias vary in severity among individuals. Some individuals can simply avoid the subject of their fear and suffer relatively mild anxiety over that fear. Others suffer full-fledged panic attacks with all the associated disabling symptoms. Most individuals understand that they are suffering from an irrational fear, but are powerless to override their panic reaction. These individuals often report dizziness, loss of bladder or bowel control, tachypnea, feelings of pain, and shortness of breath.

A specific phobia is any kind of anxiety disorder that amounts to an unreasonable or irrational fear related to exposure to specific objects or situations. As a result, the affected person tends to avoid contact with the objects or situations and, in severe cases, any mention or depiction of them. The fear can, in fact, be disabling to their daily lives.

The fear or anxiety may be triggered both by the presence and the anticipation of the specific object or situation. A person who encounters that of which they are phobic will often show signs of fear or express discomfort. In some cases, it can result in a panic attack. In most adults, the person may logically know the fear is unreasonable but still find it difficult to control the anxiety. Thus, this condition may significantly impair the person's functioning and even physical health.

Specific phobia affects up to 12% of people at some point in their life.

Unlike specific phobias, social phobias include fear of public situations and scrutiny, which leads to embarrassment or humiliation in the diagnostic criteria.

Main features of diagnostic criteria for specific phobia in the DSM-IV-TR:

- Marked and persistent fear that is excessive or unreasonable, cued by the presence or anticipation of a specific object or situation (e.g., flying, heights, animals, receiving an injection, seeing blood).

- Exposure to the phobic stimulus almost invariably provokes an immediate anxiety response, which may take the form of a situationally bound or situationally predisposed panic attack. In children, the anxiety may be expressed by crying, tantrums, freezing, or clinging.

- The person recognizes that the fear is excessive or unreasonable. In children, this feature may be absent.

- The phobic situation(s) is avoided or else is endured with intense anxiety or distress.

Specific Phobia – DSM 5 Criteria

- Fear or anxiety about a specific object or situation (In children fear/anxiety can be expressed by crying, tantrums, freezing, or clinging)

- The phobic object or situation almost always provokes immediate fear or anxiety

- The phobic object or situation is avoided or endured with intense fear or anxiety

- The fear or anxiety is out of proportion to the actual danger posed by the specific object or situation and to the sociocultural context

- The fear, anxiety, or avoidance is persistent, typically lasting for 6 months or more

- The fear, anxiety, or avoidance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning

- The disturbance is not better explained by symptoms of another mental disorder, including fear, anxiety, and avoidance of situations associated with panic-like symptoms or other incapacitating symptoms; objects or situations related to obsessions; reminders of traumatic events; separation from home or attachment figures; or social situations