He works as a diver – how can he fast when water may enter his throat?
Question

                I work as a diver in the sea every day, and sometimes drops of seawater enter my mouth and reach my throat, but they do not enter the stomach. Does this invalidate my fast? If I am not able to fast because of my work, what should I do?.
Praise be to Allah.Firstly: 
In the 
    answer to question no. 39232, we have stated that there is nothing wrong with a fasting person 
    diving into water, but he must take care to avoid letting water reach his 
    stomach as much as he can. 
Secondly: 
The Ramadaan 
    fast is one of the pillars of Islam and it is not permissible for a Muslim 
    to neglect his fast or be heedless about it because of difficulty 
    encountered as a result of his work. What he must do is strive to combine 
    fasting and work if possible. If that is not possible and he needs to work, 
    then he must give priority to fasting, and take a break from work if he can. 
    If that is not possible and he needs to work, then he should form the 
    intention to fast from the night before and start fasting in the morning, 
    then when it becomes too difficult for him, it is permissible for him to 
    break his fast because of necessity, but he has to make up that day. If it 
    does not become too difficult and he is able to complete the fast, then he 
    must do so. 
See the 
    answer to question no.  43772. 
See also 
    Fataawa al-Lajnah al-Daa’imah, 10/234. 
Thirdly: 
If a fasting 
    person swims in water and water reaches his throat without him intending it 
    to, then this does not break the fast, because he did not do it 
    deliberately. This is the view of Imam Ahmad (may Allaah have mercy on 
    him). 
See: 
    al-Mughni, 3/358; al-Insaaf, 7/434; al-Sharh al-Mumti’, 
    6/393 
Fourthly: 
The 
    questioner says that water reaches his throat but it does not enter his 
    stomach.
 The 
    scholars differed concerning the things that invalidate the fast – is what 
    counts whether the food or drink reaches the throat or the stomach? 
Shaykh Ibn 
    ‘Uthaymeen (may Allaah have mercy on him) said in al-Sharh 
    al-Mumti’ (6/393): The author (may Allaah have mercy on him) mentioned 
    six issues in which the ruling depends on whether water reaches the throat 
    of the fasting person. So the ruling is based on whether water reaches the 
    throat, not the stomach. The apparent meaning of the words of Shaykh 
    al-Islam Ibn Taymiyah is that the ruling is based on whether the thing that 
    breaks the fast reaches the stomach. There is no doubt that this is what is 
    meant, as there is no report in the Qur’aan or Sunnah which suggests that 
    the ruling is based on whether it reaches the throat, but the fuqaha’ (may 
    Allaah have mercy on them) said that if it reaches the throat it may be 
    assumed that it has reached the stomach, or that the ruling is based on 
    whether the thing that breaks the fast reaches any inner part of the body 
    and the throat is an inner part. End quote. 
Conclusion: 
There is 
    nothing wrong with swimming or diving deep into water when fasting. If any 
    water reaches the throat or the stomach without you intending it to, then 
    this does not break the fast. 
And Allaah 
    knows best.