What does an Aquarium in a dream mean?

Water symbolizes emotions - perhaps you have "Contained your emotions" about an issue.
Vulnerability - everyone staring at you and having nowhere to hide.
An aquarium in a dream can indicate you are feeling like your emotions are 'on display' for everyone to see.
Fish in an aquarium can symblize transformation - are you feeling like an important emotional transformation has been happening in front of an audience?

'Waves of emotions' - water usually represents emotions
Are you being overwhelmed by strong emotions like anger or fear?

See 'Water'

What does Diving mean in a dream?

Diving in a dream can represent:
"Taking the plunge"
Exploring inner self 
Going deeper
Are you experiencing a breaking?

See "Water" and "Swimming"

What does a Waterfall mean in a dream?

A Waterfall in a dream can represent:
Complete healing
Emotional release
Emotional recharging

What does Water mean in a dream?

Water in a dream can represent:
Your emotional energy
Your intuition
Spiritual alignment and attunement
Your unconscious self
‘The waters of life’
Purifying

What does Drowning in a dream mean?

Drowning in a dream can represent:
Being overwhelmed by your emotions.
Are you ‘drowning in your sorrows'?

See also 'Water'

What does a Boat in a dream mean?

A Boat in a dream can represent:
Boats in dreams can represent that you are navigating your emotions.
Navigating rough waters of life
A Boat in a dream can be an indication of how well you are handling the situations in your life emotionally:
Sailing through life
'Smooth sailing'
Drifting aimlessly
'Don't rock the boat'
'Missed the boat'