It has been narrated on the authority of Abu Huraira that the, Messenger of Allah (ﷺ) said
While a man walks along a path, finds a thorny twig lying on the way and puts it aside, Allah would appreciate it and forgive him The Prophet (ﷺ) said: The martyrs are of five kinds: one who dies of plague; one who dies of diarrhoea (or cholera) ; one who is drowned; one who is buried under debris and one who dies fighting in the way of Allah.
It has been narrated on the authority of Abu Huraira (through another chain of transmitters) that the Messenger of Allah (ﷺ) said
Whom do you consider to be a martyr among you? They (the Companions) said: Messenger, of Allah, one who is slain in the way of Allah is a martyr. He said: Then (if this is the definition of a martyr) the martyrs of my Umma will be small in number. They asked: Messenger of Allah, who are they? He said: One who is slain in the way of Allah is a martyr; one who dies in the way of Allah, is a martyr; one who dies of plague is a martyr; one who dies of cholera is a martyr. Ibn Miqsam said: I testify the truth of your father's statement (with regard to this tradition) that the Prophet (ﷺ) said: One who is drowned is a martyr.
A version of the tradition narrated on the authority of Suhail contains the additional words
" And one who is drowned is a martyr."
Another version of the tradition narrated on the authority of Suhail thouch a different chain of transmitters contains the additional words
" A drowned person is a martyr."
It has been narrated on the authority of Hafsa daughter of Sirin who said
Anas b. Malik asked me the cause of death of Yahya b. 'Abu 'Amra. I said: (He died) of plague. He said: The Messenger of Allah (ﷺ) said that death by plague is martyrdom for a Muslim.
This hadith has been narrated on the authority of 'Asim through the same chain of transmitters.